252 PROTOPLASM 



alligator, of Carnoy (1880) on the egg of Cyprinus, and of 

 van Beneden on the ovum of Lepus cuniculus (1880) and 

 Ascaris mcgalocepliala (1883). In most of these cases it is 

 only a superficial cortical zone of the protoplasm of the 

 ovum which shows the radial striation ; the same is usually 

 the case, as we have already described, in the central 

 capsule of Thalassicolla and many other Eadiolaria. Such a 

 radial striation can therefore hardly be brought into con- 

 nection with the centrosome, situated as it is in all cases in 

 the vicinity of the nucleus, for the radial striation, which 

 has the centrosome as its starting-point, is always character- 

 ised by being most distinct in its neighbourhood and 

 becoming more indistinct with increased distance from it, 

 since it first makes its appearance close to the centrosome 

 and commences to spread out centrifugally. The above- 

 mentioned radiate striation of the ova, on the contrary, is in 

 general most distinct at the surface of the cell, and 

 diminishes in sharpness towards the centre, which, as has 

 been pointed out, it never reaches as a rule. From this 

 fact we must certainly conclude that the cause of the 

 radiation has its seat at the surface of the egg cell, i.e. that 

 diosmotic processes between the surrounding medium and 

 the surface of the ovum produce the phenomenon. In har- 

 mony witli this is the fact especially emphasised by van Bene- 

 den, and observed by him in Ascaris megalocephala, namely, 

 that the radiate striation is not concentrated upon the often 

 excentrically placed germinal vesicle. I would further point 

 out that the drops of oil-lather often show the same appear- 

 ance, which, from all that we know, owes its origin without 

 doubt to such processes. 



There are, however, also radiating appearances in the 

 interior of the protoplasm, which, as far as we can judge of 

 them, are not produced by central bodies, or at least are not 

 exclusively caused by them. It is well known that the 

 radiating appearances which arise during fertilisation round 

 the male and female pronucleus, usually spread out evenly 

 and on all sides round these nuclei, although it is quite cer- 

 tain from recent observations that they are originally pro- 

 duced from the central bodies. If, however, this were also 



