Journal of Applied Microscopy. 339 



nucleus forms one. What observers have mistaken for a centrosome is either a 

 nucleolus just emerged from the nucleus or a remnant of the spermatic enchy- 

 lema. The last proposition is answered by the authors' assertion that the 

 centrosome disappears after each karyokinetic act. The true conditions of 

 fertilization are, therefore : (1) That the female element lacks, not a centrosome, 

 since it can supply one from its own nucleus, but a certain amount of chromatin. 

 In maturation it has lost three-fourths by weight, if not always in number, of 

 this material. The male element also, as a result of the last two divisions in 

 spermatogenesis, contains only one-fourth of the normal amount in the sperm 

 mother cell. Now, if we suppose that during the repose previous to segmenta- 

 tion, there is a doubling up in the amount of chromatin as occurs in other 

 nuclei in repose, the necessary quantity will be at hand before the first cleavage. 

 (2) The presence of the spermatozoid is -necessary that the two centrosomes 

 (maternal and paternal ?) may be formed. A third condition seems, from 

 evidence furnished by experimentation, to be necessary, namely, that before the 

 female cytoplasm has the power to divide, it must be acted on by the male 

 cytoplasm. The reason the female cell does not proceed to form the new 

 individual before fertilization is therefore that it lacks : (tr) half the normal 

 amount of chromatin, (/-) a spermatic centrosome, (<) a chemical working-over of 

 its cytoplasm. Fertilization is, then, a fusion of the two cells, nucleus with 

 nucleus, and cytoplasm with cytoplasm, for the purpose of supplying what is 

 wanting in the female cell. 



The bearing of such phenomena on the theory of heredity would be evident. 

 Since heredity may be defined as the faculty which fertilized eggs have of pro- 

 ducing beings similar to both parents, and since, as they believe, the two sexual 

 elements completely fuse, one with the other, Carnoy and Lebrun conclude that 

 maternal and paternal characters are transmitted with equal " force " because the 

 fertilized egg is a mixed element, and that the " substratum " of heredity is not 

 the chromatin alone nor the nucleus alone, but the whole cell. 



University of Pennylvania. 



J. R. MURLIN. 



A Simple Hydrogen Generator. 



Some months since, while at the Pasteur Institute in Paris, I noticed the 

 apparatus devised, I think, by Professor Roux, which they use for the evolution 

 of hydrogen. This seemed so much more simple, inexpensive, and permanent 

 in its working than Kipp's, that I thought it worth calling attention to in these 

 columns : /• is a large three-niouthed Wolff bottle more than half full of chemically 

 pure zinc ; / is a two-mouthed Wolff bottle filled with sulphuric acid and water. 

 To operate the apparatus a rubber tube connected with a water vacuum pump 

 is attached ,to glass tube a. The vacuum thus created in bottle /• causes the 

 acid mixture in bottle / to pass through tubes e and c into bottle k. Hydrogen 

 is at once evolved, which passes through tube /^ with rubber connection, to 

 bottle g containing a solution of caustic potash, to bottle /?, with a solution of 



