674 INTERNAL SECRETIONS AND PRESERVATION OF LIFE. 



The same correspondence exists between nerve-fibrils and 

 the mitoma when hasmatoxylin is used. We have seen (page 

 536) that, according to McCarthy, the rods that project radially 

 from the axis-cylinder "stain with carmine and haematoxylin, 

 which do not stain the myelin." The fact that the axis-cylinder 

 takes haematoxylin hardly needs to be emphasized, its use in 

 histological laboratories when nervous structures are studied 

 being second only to picrocarmine for general staining. A 

 beautiful example of haBmatoxylin-stained human cerebro- 

 spinal and sciatic nerves is to be found in Clarkson's "Histol- 

 ogy," page 204, for instance. All the eosinophile leucocytes 

 shown in the annexed plate, in which the nuclear and the peri- 

 nuclear granules and mitoma are so clearly defined, were stained 

 with Heidenhain's iron-haematoxylin, which only differs from 

 the usual solution in that it colors the cellular elements that 

 take it a dark gray or black. This also shows that it is not only 

 with the mitoma of basophile leucocytes that the staining char- 

 acteristics of nerve-fibrils i.e., plasma-containing channels 

 coincide, but also with that of eosinophile cells. Even Apathy's 

 fibrils are recalled by the effects of corresponding stains, for 

 Senn writes, 7 referring to the minute anatomy of the leuco- 

 cyte: "The reticulated structure is well shown by staining with 

 chloride of gold, which stains the protoplasmic strings, but not 

 the interstitial substance." It seems to us quite evident, there- 

 fore, that the mitoma, i.e., the intracellular and intranuclear net- 

 works of fibers in mature leucocytes, are canaliculi for Hood-plasma 

 and for the substances contained in this fluid. 



FUNCTIONAL MECHANISM OF THE LEUCOCYTE. We have 

 expressed the view that the nuclear canaliculi open into a 

 vacuole which surrounds the nucleus (see Fig. 14 in Gulland's 

 plate) and that the outer wall of this vacuole acts as terminal 

 for some of the canaliculi of the cell-substance. Although, as 

 suggested by Fig. 11, the canalicular orifices that open into 

 the vacuole from both directions may correspond (the nuclear 

 orifices being in that case opposite the cellular openings), such 

 is by no means always the case. Indeed, in Fig. 16, for exam- 

 ple, but two or three of the external canaliculi seem to be con- 



7 Senn: "Principles of Surgery," third edition, 1901. 



