The Smear Technic in Plant Cytology

The following method of making permanent smears of pollen mother cells is in general use and gives excellent results. Determine the stage of meiosis from aceto-carmin mounts. Smear the pollen mother cells on a dry slide. Fix in Navaschin's or a modified Flemming's solution from 1 to 2 hours. Wash in 10 to 20% alcohol from 15 to 30 minutes. Stain in 1% aqueous crystal violet from 1 to 5 minutes. Rinse in water and pass thru 30 to 50% alcohol, about 15 to 20 seconds in each. Transfer to 80% alcohol containing 1% iodine and 1% potassium iodide for 30 seconds. Destain with absolute alcohol, followed by clove oil. xylol, balsam and cover.

Permanent smears for chromosome counts can be quickly made by smearing pollen mother cells on a dry slide, fix and stain with aceto-carmin, dehydrate with mixtures of absolute alcohol and acetic acid, follow with xylol, balsam, and cover.     

The Functional Cytology of the Human Adenohypophysis

Using a combination of cytological, cytochemical and immunohistological techniques, an endeavour has been made to localize the sources of production of the seven protein and polypeptide hormones of the anterior pituitary gland. For growth hormone, TSH and ACTH, this has been done with reasonable certainty, and FSH and LH have been confirmed as coming from the mucoid cells. Although each of the hormones may be derived from a single cell type, present evidence has suggested that three or perhaps four cell types share the production of the seven known hormones and of any which remain to be discovered.     

The Cytology of a New Species of Spirostomum

SUMMARY. A study has been made of the cytology of an undescribed species of Spirostomum. The species is much smaller than S. ambiguum. The peristome extends to about half the length of the animal, whereas in S. ambiguum it is about two-thirds the body length. The nuclear apparatus reveals some striking differences. The macronucleus is cylindrical, and not chain-like, in the vegetative animal. The micronuclei are far fewer than in S. ambiguum and number 6–15, but are larger in size. During binary fission, the macronucleus becomes condensed into an oval or polymorphic mass and is drawn out again into a cylinder before it is cut into two lengths. The micro-nuclei divide by mitosis and, whatever their number in the vegetative animal, only 7–8 take part in the division. The others presumably degenerate.     

Cytology of oomycetes

Evidence is presented for gametangial meiosis in six Oomycetes. Particular attention is drawn to late meiotic prophase stages (pachytene-diplotene) in which chromomeres and paired homologues can be seen. One of these Oomycetes has been shown to have an abortive meiosis. Multiple chromosome associations (quadrivalent configurations, with some trivalent and univalent configurations) at first metaphase with unequal divisions at first telophase or second metaphase suggest that autopolyploidy is to be found in several species. Allopolyploidy is suspected at intermediate levels of ploidy. Basic chromosome numbers of n=3 for Achlya and n=10 for Pythium are proposed.