502 SUMMARY OF CURRENT RESEARCHES RELATING TO 



have something to do with determining a tendency to parthenogenesis 

 during the period before liberation. 



Chemical Composition of Germ-Cells and that of Solutions in- 

 ducing' Parthenogenesis.* — Yves and Marcel Delage, referring to 

 Loeb's experiments on the parthenogenetic effect on sea-urchin ova of 

 solutions of magnesium chloride in sea-water, have inquired into the 

 chemical composition of the germ-cells of the sea-urchin (Strongylo- 

 centrotus lividus), to see how the sperm stands as regards magnesium. 

 The analysis shows that the proportions of this metal in the sperms 

 and in the ova are not sensibly different. If there is a difference, it is 

 rather in favour of the ova. The authors note that Loeb has mean- 

 while suggested that the solution acts not by any specific chemical 

 influence, but solely by an alteration in the osmotic pressure. 



Heredity and Disease.f — Prof. J. G. Adami discusses, from a patho- 

 logist's point of view, Weismann's theory of inheritance, with special 

 reference to the transmission of acquired conditions in man. Medical 

 men, he says, all admit that " inheritance plays a part in the develop- 

 ment of morbid conditions," but are " unwilling to discuss or write about 

 the exact part played by it." Perhaps the reason is that man is not a 

 good subject for investigation ; he breeds very slowly ; and, as with other 

 placentals, there are complications introduced by maternal influence 

 during the uterine life. Thus medical men have had to depend upon 

 biologists, whose theories " have assumed shapes which would not dis- 

 grace the schoolmen of the Middle Ages." 



Prof. Adami states Weismann's theory of heredity and part of his 

 theory of development. " So far as regards the ids, the brilliant ob- 

 servations of Driesch, abundantly confirmed by others, show that the 



conception is untenable The existence of these hypothetical ids 



is absolutely disproved." [It should have been noted, however, that re- 

 conciliations between Driesch's facts and the hypothesis have been at 

 least attempted by Weismann, Eoux, and others.] Prof. Adami states 

 Weismann's theory even by quotation, yet he writes in exposition, 

 " However much a man abuses his soma or body is of little moment, 

 the effect upon the offspring is minimal." [This seems an extreme 

 statement, seeing that Weismann admits the possibility of infection of 

 the germ, e.g. by the specific bacteria of syphilis, the possihilty of 

 climatic and other influences affecting both soma and germ-cells, aud 

 the possibility that nutritrive changes in the soma may prompt varia- 

 tions in the germ-plasm.] 



Adami has thought out an independent theory of heredity, which 

 may be summed up as follows. Distinguishing the essential and direc- 

 tive living matter of an organism as its idioplasm in contrast to the 

 less vital cytoplasm, recognising also that the idioplasm has come to 

 have in the course of evolution an increasing complexity of constitution, 

 and that in spite of its relative constancy it is capable of being changed 

 by environmental influence, the author asks, " Can we imagine a chemical 

 substance so constituted as to be capable of modification in its mole- 

 cular constitution — and so in sundry of its properties — without under- 

 going complete change, without other properties being lost?" He finds 

 an analogy in the different forms of various organic substances, such 



* Comptes Rendus, exxxi. (1900) pp. 1227-9. 

 t Brit. Med. Journ., June 1st. 1901, pp. 1317-23. 



