190 PHYSIOLOGICAL CHEMISTRY. 



1. Crystals from all species of a certain genus have certain 

 characteristics in general. Crystals from different genera however 

 exhibit marked differences in system, axial ratios, etc. 



2. Crystals of different species of a genus may generally be 

 differentiated by difference in the angles. 



3. The oxyhaemoglobin of some species crystallizes in several 

 types of crystals in the same preparation. Generally the crystals 

 first formed belong to a system of a lower grade of symmetry than 

 those formed later. When such different types of crystals occur 

 they may be arranged in isomorphous series. 



4. Certain definite angles recur in the crystals from the blood 

 of various species of animal, although the zoological connection 

 may be remote and the crystals belong to different systems. 



5. The constant recurrence of certain types of " twinning " 

 in all the crystalline forms was observed. 



6. Differences have been observed in the crystalline form of 

 oxyhaemoglobin and haemoglobin from the blood of the same 

 species in certain cases. 



The following bodies may be derived from haemoglobin, and each 

 possesses a specific spectrum which serves as an aid in its detection 

 and identification : Oxyhaemoglobin, methaemoglobin, carbon-mon- 

 oxide haemoglobin, nitric-oxide haemoglobin, haemochromogen, 

 haematin, acid-haematin, alkali-haematin and haematoporphyrin (see 

 Absorption Spectra, Plates I and II). 



The white corpuscles (or leucocytes) of human blood differ from 

 the red corpuscles (or erythrocytes) in many particulars, such as 

 being somewhat larger in size, in containing at least a single nucleus 

 and in possessing amoeboid movement (see Plate IV, opposite page 

 184). They are typical animal cells and therefore contain the fol- 

 lowing bodies which are customarily present in such cells : Proteins, 

 fats, carbohydrates, lecithin, cholesterol, inorganic salts and water. 

 The normal number of leucocytes in human blood varies between 

 5,000 and 10,000 per cubic millimeter. The ratio between the leu- 

 cocytes and erythrocytes is about i : 350-500. A leucocytosis is 

 said to exist when the number of leucocytes is increased for any 

 reason. Leucocytoses may be divided into two general classes, the 

 physiological and the pathological. Under the physiological form 

 would be classed those leucocytoses accompanying pregnancy, par- 

 turition and digestion, as well as those due to mechanical and ther- 

 mal influences. The leucocytoses spoken of as pathological are the 

 inflammatory, infectious, post-haemorrhagic, toxic and experi- 



