PHYSIOLOGICAL 335 



wise with the modern experiments on inducing artificial partheno- 

 genesis by means of chemical reagents. For the chemical provocatives 

 are so diverse that they do not in themselves throw any light on 

 what results — the launching of an unfertilised egg on the voyage of 

 development. When Delage added tannin and ammonia to the 

 sea-water in which unfertilised sea-urchin eggs were floating, they 

 began to segment and develop, and when they were restored to 

 normal sea- water the development went on apace and quite normally, 

 so that fatherless sea-urchins were reared. But Loeb did the same 

 by subjecting the eggs of sea-urchins for a very short time to the 

 influence of butyric acid, and then restoring them to normal sea- 

 water. There are other ways in which artificial parthenogenesis can 

 be brought about, but they do not yet throw much light on the 

 normal process of fertilisation. One can say this much, however, 

 that what the living sperm effects, as far as stimulus goes, may be 

 effected by chemical reagents. 



It is not always easy to draw a line between help with a chemical 

 method and help with a chemical idea; and an illustration of this 

 may be useful. A Russian physiologist. Dr. E. O. Manoilov, claims 

 to have discovered a reaction by which it is possible to distinguish 

 the blood of a female from the blood of a male. To the blood in a 

 test-tube one adds in succession some papayotin, some methyl- 

 green, some potassium permanganate, some hydrochloric acid, and 

 some thiosinamin (it is unnecessary to mention the strengths and 

 quantities). The outcome is that the blood of the male soon becomes 

 colourless or nearly so, while the blood of the female retains its 

 reddish colour. This has been verified for mice, sheep, pigeons, and 

 so on. The same is said to be true in regard to plants, with separate 

 sexes so-called, like the nettle, the dioecious Lychnis, the dog's 

 mercury, the willow, and the poplar. It has been successfully tried 

 for both animals and plants at the Cold Spring Harbour Experi- 

 mental Station in America; but tests made by one of the demonstra- 

 tors in the Aberdeen University Zoological Laboratory were quite 

 inconclusive. Some gave the right result, some the wrong, and some 

 nothing. That is by the way; for the point is this, that if the chemical 

 treatment, or another like it, does actually serve to differentiate 

 the blood of a male from the blood of a female, or the extract of a 

 male plant from the extract of a female plant, it should be possible 

 to discover the chemical reason — a discovery which would afford 

 a clue to the lasting puzzle as to the essential metabolic difference 

 between maleness and femaleness. 



A simpler test has been used by Steele and Zeimst. Hydrochloric 

 acid and an oxidising solution are added to a diluted sample of 

 blood serum in a test-tube. A few drops of methyl-green are added, 

 and if the blood is from a female the colour is green, if from a male 

 the colour is red. Twenty pigeons and seventeen cattle were tried 



