CONTRIBUTIONS TO THE CYTOLOGY OF THE BACTERIA. 477 



be desired. Nevertheless, he appears to have found organ- 

 isms possessing nuclei in the form of chromidia, spiral fila- 

 ments and spherical masses of chromatin. He also dis- 

 tinguishes between nuclei and "granulations," and points 

 out the structural variability which the nucleus displays. On 

 the whole, his observations — so far as I understand them — 

 appear to be in agreement with mine. 



Kunstler's (1887) observations upon the structure of 

 Spirilla agree closely with what I have myself described in 

 Spirilla with a chromidial type of nucleus. Also the 

 chromatin structures described in the cholera A^ibrio by 

 Podwyssozki (1893) bear a strong resemblance in many cases 

 to the nuclei which I have shown to occur in the small 

 Spirillum from the gut of Stylopyga orientalis. 



I believe the "chromatin" granules described in sulphur 

 Bacteria by Hiuze (1901, 1903) and Dangeard (1909) are- 

 like Biitschli's findings in similar forms — to be interpreted as 

 nuclei in a chromidial condition. The same interpi-etation 

 will apply to the granules of B. oxalaticus, described by 

 Migula (1894) ; and also to the iron- and phosphorus-containing 

 granules found in Beggiatoa by Macailum (1899).^ 



Kowland's (1899) results can easily be explained if it be 

 supposed that the organisms which he studied possessed 

 nuclei in the form of chromidia in addition to metachromatic 

 bodies. 



I think I may fairly claim, from what I have already 

 pointed out in the preceding pages, that not only do my own 

 observations furnish most conclusive evidence with regard to 

 the nucleus in Bacteria, but that in almost every case in 

 which careful investigation has been made by others, the 

 results are not inconsistent with mine. In many cases they 

 are, indeed, completely confirmatory. When good technique 

 has been employed, and careful observations have been made, 



' Certain points in connection with fixation are, moreover, not quite 

 clear to me in the work of this author. It may also be pointed out that 

 Macailum failed to find a nucleus in the yeasts — in which a typical 

 vesicular nucleus certainly occurs. 



