348 SPECIAL HISTOLOGY. 



\The investigation of the heart, as regards the muscular fibres 

 themselves, is easy, and their anastomoses will be found without 

 difficulty in every carefully made preparation. But great 

 difficulties attend the tracing of the course of the fibres in that 

 organ. Hearts that have been macerated in weak spirit are 

 best adapted to this purpose ; the boiling in water, also, of the 

 recent heart, or of hearts that have been previously in salt for 

 some weeks, has been long recommended, a method, instead of 

 which Purkinje and Palicki advise the boiling in a solution of 

 common salt, or still better of sulphide of lime; whilst Lud wig, 

 after removing the pericardium, lays the heart in water, and 

 repeats this maceration each time after the removal of a layer 

 of the muscular substance, using at the same time slight 

 pressure. For the blood-vessels, the tearing of them into 

 lamellae with the forceps and scalpel, which alone was formerly 

 employed, is not sufficient ; the examination of transverse and 

 longitudinal sections of the entire wall, being, in addition, 



stages ; but two of the latter, that of the coloured nucleated cell and that of the 

 colourless free cellae-form nucleus, occur but rarely and scantily. That the red cor- 

 puscle of Mammals is the cellae-form " nucleus" of the nucleated-cell stage, set free 

 by the bursting of this cell itself, and become filled and red by the secretion of 

 globulin and colouring matter into its interior, is strongly evidenced by the cor- 

 respondence in size between the " nucleus" and the red corpuscle, as the latter varies 

 in different animals. In the Elephant the red corpuscle is very large, and in the 

 Goat it is veiy small ; the " nucleus" of the colourless corpuscle varies correspond- 

 ingly. There is a similar correspondence in form ; and it is remarkable that in the 

 Paco, whose red corpuscles are, when fully formed, elliptical, while the nuclei of the 

 colourless corpuscles are for the most part circular, younger less-coloured red cor- 

 puscles are met with, which are circular and correspond in all respects with the 

 " nuclei" of the colourless corpuscles. In dealing with objections which might be 

 raised from the chemical and physical differences between the red corpuscles and the 

 "nuclei," Wharton Jones shows that these almost disappear if we select the 

 youngest state of the red corpuscle as one term of the comparison. 



It is rare to meet with the transition stage between the phase of nucleated cell 

 and that of " free cellae-form nucleus," in the blood of Man. We have, however, 

 recently recorded an observation of the kind in unaltered blood (' Quarterly Journal 

 of Micr. Science,' vol. i, p. 145), where a well marked red corpuscle was observed within 

 what would otherwise have been regarded as a colourless corpuscle, and occupying 

 the place of its " nucleus ;" and we may add that the same subject has recently 

 afforded, in blood taken from the finger one or two hours after breakfast, a very con- 

 siderable proportion of such corpuscles with red " nuclei," affording every transitional 

 stage between the ordinary colourless corpuscle and the free red cellae-form nucleus. 

 For these observations, however, water and very dilute acetic acid were added to the 

 blood. — Eds.] 



