Oogenesis in the Apogamous Fern Pteris cretica

The events that characterize egg formation and maturation inPteris cretica were investigated using transmission electronmicroscopy and electron microscope microprobe analysis. Theydid not differ significantly from those described for sexuallyreproducing ferns. The significance of these findings is discussedin relation to current theories concerning phase change in ferns. Pteris cretica, fern, apogamy, agamospory, transmission electron microscopy, oogenesis     

Plasma Amino-acids in the Nigerian Nutritional Ataxic Neuropathy

Investigation of nine patients with tropical ataxic neuropathy showed an absence or diminution of sulphur-containing amino-acids—cysteine and methionine—and a variable concentration of most other essential amino-acids. The pattern was unlike that found in kwashiorkor. The levels of serum cholesterol and total protein were normal, and the serum vitamin B₁₂ levels were normal or high. Plasma thiocyanate concentration was high.All the patients gave a history of a monotonous diet of cassava derivatives. Cassava contains a cyanogenetic glycoside (linamarin) from which cyanide is released on hydrolysis. The excessive cyanide detoxication may be responsible for the low concentration of the sulphur-containing amino-acids.