SECT. 6] OF THE EMBRYO 845 



to demonstrate it. For Triton marmoratus egg-cells Parat gives a 

 />H of 7-2-7'3 for the protoplasm, but of G-S-G-g for the vacuome: 

 for Ascidia mentula egg-cells 6-8 and 5-0 respectively (vital staining). 

 (Only four complete studies of the behaviour of the Golgi apparatus 

 during embryonic development exist: Gatenby and Hirschler on 

 Limnaea stagnalis, Nihoul on the rabbit, Parat on the nudibranch 

 molluscs Aplysia and Polycera.) Finally, Drzwina & Bohn have de- 

 scribed a phenomenon which may be called "infectious cytolysis". 

 If a number of small animals, such as planaria, or of eggs, are placed 

 in a small space, it is found that the cytolysis of a few sets all the rest 

 cytolysing, and these workers found that a culture of Convoluta by its 

 cytolysis lowered the pB. of its culture medium from 7-0 to 4-4 in 

 two minutes. Similar observations were made by Rebello and by 

 Drastich. In our own experiments we observed that when amoebae 

 cytolysed, their internal />H went down from 7-6 to about 5-0, but 

 when the marine egg-cells cytolysed their pH descended further and 

 more rapidly from 6-6 to about 4-5. This has since been confirmed 

 by Reznikov & Pollack. On these grounds we concluded that our 

 more alkaline figures were more accurate than Vies' acid ones. We 

 laid some emphasis on the fact that we observed no change in the 

 intracellular /?H on fertilisation, and that, although we micro-in- 

 jected blastomeres up to the morula stage, we never found any 

 perceptible variation during the cleavage period. The intercellular 

 fluid in the i6-cell stage and the liquid filling the blastocoele cavity 

 we found to be at least as alkaline as pYi 7-3. This was almost exactly 

 the same figure as one previously obtained for the blastocoele of 

 Pomatoceros by Horstadius. 



Certain other points also emerged from our work on these marine 

 invertebrate eggs. If the egg-cells of Asterias were fertilised with 

 concentrated sperm suspensions, and afterwards kept in conditions 

 of bad oxygenation, a high percentage of abnormal forms made 

 their appearance, protruding bulbs of protoplasm, dumb-bell shapes, 

 abnormal divisions, etc. But in all these cases the intracellular j^H 

 was normal, and remained so until cytolysis set in, when it was, of 

 course, lowered to/?H 4-5, or below. Again, in injections of the 2-cell 

 stage in Strongylocentrotus, one blastomere would be quite coloured 

 with the dye used, and would even cytolyse before its fellow showed 

 any abnormality. There was no connection between them. Then we 

 found that in acid sea water of p¥L 6-o the eggs would remain for at 



