ITS CHEM1CO-PHYSICAL AND MORPHOLOGICAL PROPERTIES 15 



mass, it has been thought advisable to distinguish two kinds of 

 protoplasm, the ectoplasm or hyaloplasm, and the endoplasm or 

 granularplasm (Fig. 2, ek, en). 



Many investigators, such as Pfeffer, de Vries, etc., are inclined 

 to consider that this peripheral layer is a specially differentiated organ 

 of the cell and is endowed with special functions. The following 

 experiment which I have made seems to bear out this view. 



Some ripe eggs of Rana temporaria, which had entered the 

 oviduct and were surrounded with a gelatinous coating, were care- 

 fully pierced with the exceedingly fine point of a glass needle. 

 The puncture thus made was not visible externally after the 

 operation, nor was any yolk seen to exude through the holes. 

 However, some time after fertilisation of the eggs had taken place, a 

 fair quantity of yolk began to make its way out of all the punctured 

 eggs, and to form a more or less large ridge (extraovat, Roux) 

 between the membrane of the egg and the yolk. This welling out 

 of the yolk substance was induced by the act of fertilisation, for the 

 entrance of the spermatozoon stimulates the surface layer to con- 

 tract energetically, as may be easily demonstrated under suitable 

 conditions. Hence the puncture must have caused a wound in the 

 peripheral layer, which had not time to heal before fertilisation 

 took place, and through which the yolk was only pressed out after 

 the contraction caused by the fertilisation had taken place. Now 

 since between the piercing of the eggs and their fertilisation a 

 fairly long interval, which however I did not accurately measure, 

 had elapsed, this experiment seems to show that the peripheral 

 layer possesses a structure differing somewhat from that of the rest 

 of the cell contents, and also that it has properties peculiar to 

 itself. 



c. Chemical Composition of Protoplasm. Our know- 

 ledge of the chemical nature of protoplasm is most unsatisfactory. It 

 has sometimes been described as an albuminous body, or as " living 

 albumen." Such expressions may give rise to utterly incorrect 

 conceptions of the nature of protoplasm. On this account I will 

 recapitulate what I said in section a : Protoplasm is not a 

 chemical, but a morphological conception; it is not a single 

 chemical substance, however complex in composition, but is com- 

 posed of a large number of different chemical substances, which 

 we have to picture to ourselves as most minute particles united 

 together to form a wonderfully complex structure. 



Chemical substances exhibit similar properties under different 



