232 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. II. 



in such cases it is difficult or even impossible to get any reactions at all 

 with the Indigo-carmine Fluid. 



In preparations of the blood, therefore, made with corrosive sublimate, 

 osmic vapor, and Erlicki's Fluid, and subsequently stained with. the 

 Indigo-carmine Fluid, the nuclei of the red cells are shown to contain 

 two substances : one which stains grass-green or blue-green arranged as 

 a network, the other colored red (light or deep), situated in the spaces 

 formed by the network. 



It is now pertinent to ask whether the nuclear network is formed o^ 

 or contains haemoglobin, or whether, as it may happen to be chromatin, 

 it, as such, merely shows a special affinity for sodic sulphindigotate, 

 without pointing to any relationship between it and haemoglobin. I 

 have already stated in the description of the fresh and living red cell 

 that its nucleus frequently presents, under oil-immersion objectives, a 

 straw-yellow network which is seen in contrast with the slight pale- 

 ness of the rest of the nuclear substance. This would seem to indicate 

 the existence of haemoglobin in the nuclear network. That it is not 

 haemoglobin, though a substance allied to it — judging from its color 

 in the fresh cell and its reactions with sodic sulphindigotate in the 

 fixed cell — is shown by the employment of picric acid as a fi.xative 

 reagent on cover preparations and the use of the Indigo-carmine Fluid. 

 In such the discs of the red cells are somewhat vacuolated but they are 

 colored grass-green while their nuclei are either light red with a deep red 

 network, or, sometimes, light blue with a deep red network. If haemo- 

 globin is present in the nucleus it ought in picric acid preparations to be 

 as readily detectable there as in the disc. 



The question now advanced is : what is the composition of the 

 substance forming the nuclear network and of that filling its meshes? 



If a section of the spleen hardened in chromic acid is stained with the 

 Indigo-carmine Fluid, the discs of the red cells appear faint red while 

 their nuclei are colored a deep grass-green. In the latter there is not 

 the slightest trace of a differentiation into network and mesh substance. 

 Evidently then the employment of chromic acid has converted the whole 

 of the nuclear substance into something which stains grass-green with 

 the Indigo-carmine Fluid The latter reagent is not the only one which 

 shows this conversion for alum-haematoxylin, alum-cochineal and safranin 

 stain homogeneously the nuclei of ^the red cells of such preparations. 

 The whole of the nucleus, both network and mesh substance, must 

 be regarded therefore, as modified chromatin or as a mixture of 

 chromatin and achromatin, the latter being rendered capable by the 

 chromic acid of absorbing staining matters. That we have nothing to 



