THE CENTROSOME 311 



The discrepancy between these results on the part of the two 

 pioneer investigators of the centrosome has led to great confusion 

 in the terminology of the subject, which has not yet been fully 

 cleared away. Many of the observers who followed Boveri (Flem- 

 ming, Hermann, Van der Stricht, Heidenhain, etc.) found the centro- 

 some, in various cells, as a much smaller body than he had described, 

 often as a single or double minute granule, staining intensely with 

 iron-haematoxylin. Heidenhain ('93, '94) and Driiner ('94, '95) found 

 further that the asters in leucocytes and other forms often show 

 several concentric circles of microsomes, and that the sphere bounded 

 by the innermost circle often stains more deeply than the outer por- 

 tions and may appear nearly or quite homogeneous (Fig. 156). To 

 this sphere, with its contained central granule or granules Heidenhain 

 applies the term microcentrum ('94, p. 463), while Kostanecki and 

 Siedlecki suggest the term microsphere ('96, p. 217). Still later 

 Kostanecki and Siedlecki ('97) found that even in Ascaris, as in other 

 forms, sufficient extraction of the colour (iron-haematoxylin) reduces the 

 centrosome to a minute granule to which the astral rays converge, 

 and which is presumably identical with Boveri's "central granule." 

 Heidenhain ('93, '94) found that in leucocytes the central granule is 

 often double, triple, or even quadruple, while in giant-cells of certain 

 kinds there are numerous deeply staining granules (Fig. 14). He 

 therefore proposed to restrict the term centrosome to the individ- 

 ual granules, whatever be their number, applying the term microcen- 

 trum to the entire group ('94, p. 463). 



With these facts in mind we can gain a clear view of the manner 

 in which both the confusion of terminology and the contradiction of 

 results has arisen. Brauer ('93) found in Ascaris (see above) that 

 division of the central granule precedes division of the "centrosome" 

 and therefore suggested that only the former is equivalent to Van 

 Beneden's " corpuscule central," while the body called "centrosome" 

 by Boveri is really the medullary astral zone, the " Heller Hof " being 

 the cortical zone. This is substantially the same conclusion reached 

 by Heidenhain, Rawitz, Lenhossek, Kostanecki and Siedlecki, Erlan- 

 ger, Van der Stricht, Lillie, and several others. The confusion of 

 the subject is owing, on the one hand, to the fact that those who 

 have accepted this conclusion continue to use the word centrosome 

 in two quite different senses, on the other hand to the fact that the 

 conclusion is itself repudiated by Boveri ('95), MacFarland ('97), and 

 Fiirst ('98). 



As regards the terminology we find that most recent writers agree 

 with Heidenhain, Kostanecki and Siedlecki, in restricting the word 

 centrosome to the minute, deeply staining granules, whether one or 

 more, at the centre of the aster. On the other hand, Brauer, Fran- 



