ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 37 



Effect on Progeny of Fowls after Treatment with Alcohol.* — 

 Raymond Pearl continues his experiments on the effect of alcohol on 

 fowls and their progeny. The parents were treated with ethyl-alcohol, 

 methyl-alcohol and ether. The proportion of fertile eggs was reduced 

 in the matings of dosed parents. The prenatal mortality was reduced ; 

 the postnatal mortality was reduced ; the sex-ratio was not sensibly 

 affected ; there was no significant difference in mean hatching weight 

 when only the male parent was treated ; the oft'spring of alcoholized 

 parents showed a higher mean hatching weight and mean adult weight ; 

 the proportion of abnormal chicks was not affected ; many germ-cells 

 of treated parents did not form zygotes, but those that did were not 

 injured in any way. There is much to be said in support of the 

 hypothesis that alcohol and similar substances act as selective agents 

 upon the germ cells of treated animals. 



Hereditary Characters and Evolution, f — H. S. Jennings takes a 

 survey of his own observations on Difflugia, and compares his results 

 with those reached by others working with Drosophila, rats, CEnothera 

 and other forms. The general impressions are the following : — 

 " 1. Experimental and observational study reveals that organisms are 

 composed of great numbers of diverse stocks differing heritably by 

 minute degrees. 2. Sufficiently thorough study shows that minute 

 heritable variations— so minute as to represent practically continuous 

 gradations — occur in many organisms ; some reproducing from a single 

 parent, others by biparental reproduction. 3. The same thing is 

 reported from palaeontological studies. 4. On careful examination we 

 find even that the same thing is revealed by such mutationist work as 

 that on Drosophila ; single characters exist in so many grades due to 

 minute alterations in the hereditary constitution as to form a practically 

 •continuous series. 5. It is not established that heritable changes must 

 be sudden large steps ; while these may occur, minute heritable changes 

 are more frequent. 6. It is not established that heritable variations 

 follow a definite course as if predetermined ; they occur in many 

 directions. 7. It is not established that all heritable changes are by 

 ■disintegration ; although many such do occur, they cannot be considered 

 steps in progressive evolution from the visibly less complex to the 

 visibly more complex. Evolution according to the typical Darwinian 

 scheme, through the occurrence of many small variations and their 

 guidance by natural selection, is perfectly consistent with what experi- 

 mental and palseontological studies show us; to me it appears more 

 ■consistent with the data than does any other theory." 



Study of Free-martin. J— Frank R. Lillie has studied the sterility 

 which is the rule, subject to a few exceptions, in the female of the 

 two-sexed twins of cattle. In such females, commonly known as free- 

 martins, the internal organs of reproduction are usually predominantly 

 male in character, and the external organs are usually, at least, of the 

 female type. There are however considerable variations. The general 



* Journ. Exper. Zool., xxii. (1917) pp. 241-310 (7 figs.). 

 t Journ. Washington Acad. Sci., vii. (1917) pp. 281-301. 

 X Journ. Exper. Zool., xxiii. (1917) pp. 371-452 (29 figs ). 



