270 BULLETIN OF THE 



ance of the accuracy of his position in the fact that he has "directly seen how apart 

 of the nuclear membrane assumes the character of the rest of the cell body, whereby 

 the contents of the nucleus become one with this cell body." This would cer- 

 tainly be most important were it sufficiently established by Strieker's observa- 

 tions. It occurs to me, however, that the direct optical properties of the living 

 protoplasm and nuclear membrane afford only one out of many criteria by 

 which to judge of the identity of the two substances. 



It were as competent to say of two fluids, that, because both are clear and of 

 like refractive properties, consequently they are identical. It will be soon 

 enough to accept Strieker's conclusions when it shall have been shown that no 

 reagents are- capable of disclosing a difference between the two substances of 

 these cells during the stages of which he speaks. 



Arnold ('78, p. 131, cf. also pp. 138, 139, and Taf. II. Fig. 1) affirms with 

 some reservation the existence of deeply colored granules and filaments in the 

 substance of the cell and nucleus of cartilage taken from animals, nnto whose 

 blood indigo-carmine (sulphoindigotate of soda) had been infused. 



Klein's ('78) studies on the newt (Triton cristatus) were mostly conducted 

 by the use of a 5 % solution of chromate of ammonia, followed by staining 

 in carmine, picrocarmine, or hsematoxylin. His results — so far as regards the 

 structure of the nuclei — are very uniform for a variety of tissues, viz. epi- 

 thelial cells of the stomach and the various components of the mesentery, 

 surface endothelium, unstriped muscle fibres, connective-tissue corpuscles, — 

 both migratory and fixed, — blood capillaries and lymphatics, and especially 

 nucleated endothelial plates investing the nerve fibres. An extremely beautiful 

 network of fibrils permeates uniformly the interior of all the epithelial nuclei, 

 " intranuclear network." The nuclear membrane is always well defined, and 

 in some instances the network does not extend quite up to it, leaving an un- 

 occupied zone. " But in all cases the network is in connection with what is 

 known as the limiting membrane by numerous fibrils." How these fibrils 

 differ from the fibrils of the network is not stated, nor why they are not an 

 integral part of the network. The following description of the nuclear mem- 

 brane seems to obliterate the distinction which was so clearly implied : " What 

 usually appears as nuclear membrane is composed of an outer thicker portion, 

 which is the limiting membrane proper, and — closely connected with it — of 

 an inner more or less incomplete — probably because reticular —delicate layer, 

 which is, properly speaking, a peripheral condensation of the intranuclear net- 

 work, with which it is, of course, connected by longer or shorter threads. The 

 clear space which may be observed in some instances between the 'membrane' 

 of the nucleus and the intranuclear network is due ... to a retraction of the 

 latter from the former, and is a space, not between the two layers of the limit- 

 ing membrane, but between the inner layer of this and the bulk of the intra- 

 nuclear network." 



The fibrils of the network are highly refractive, and vary in thickness, 

 course, and arrangement. Almost always minute bright spots — more numer- 

 ous in dense or shrunk networks -^ are to be seen ; they are points of anastomo- 



