444 BOTANICAL GAZETTE [aay 
of the term mycoplasma to designate one of the two types of protoplasm which 
he conceives to be the fundaments of which the organic world is built up. The 
article is a convenient historical summary but adds no new material to what 
has already been published. In it the author again calls attention to the fact, 
often emphasized by him, that the study of secondary rust pustules, as carried 
out by Warp and others, cannot have any bearing on the theory which is con- 
cerned only with the origin of the primary pustules. In concluding the author 
expresses a wish for a complete investigation of the whole problem 
ZACH,‘ in a paper dealing with the results of a cytological investigation of 
the pustules of Puccinia graminis and P. glumarum, comes to the conclusion 
that the mycoplasma theory is untenable and rests on a misinterpretation of 
the facts which, in themselves, he concedes are correctly described by ErRIKs- 
son. ZAacu studied microtome sections and free-hand sections of P. graminis, 
but only free-hand sections of fixed material of P. glumarum. From this 
material he-describes processes of disorganization of the tissues. At the margin 
of the rust pustules the host cells have a turbid, deeply staining protoplasm 
which he identifies with ErRIKssON’s resting mycoplasma. The nuclei of these 
cells are much hypertrophied and seem to be filled with hyphae, some of which 
extend to the cell wall. The filaments degenerate and fuse into irregular lumps. 
The nucleus decreases in size and finally becomes an amorphous homogenous 
body termed an excretion product. Similar smaller bodies occurring through- 
out the cell he regards as identical with the ‘“‘plasmanucleoli” of ERIKssoN. 
In more advanced stages the hyphae are largely dissolved, leaving only small 
amorphous particles. These processes, by which the cell and the parasite mu- 
tually destroy each other, resemble those formerly described by the author in his 
studies on the root tubercles of cycads. The process is termed phagocytosis, 
analogous to that phenomenon in animals. The figures accompanying the 
paper represent in a general way processes in cells undergoing disorganization 
as the result of the action of the fungi or other agents, which cause a slow dying 
of the cells. The “hyphae” figured bear not the least resemblance to the hyphae 
or haustoria of rusts. 
In a criticism of the foregoing paper, ERIKSSON points out that Zacu fails 
to state that he confined his studies to the primary uredo pustules, and further- 
more that the pustules investigated by him were too far advanced to show 
stages of the mycoplasma, which is present only before the pustules become 
visible. The formations observed by Zacu belong to a later stage in the life of 
the rust. The various ‘‘excreted” bodies described by Zacu, Errksson finds 
4Zacu, F., Cytologische emacs aN an den Rostflecken des Getreides und 
die Mycoplasmatheoie. Sitzungsb. K. Akad. Wiss. Wien Math.-Naturw. KI. 
119:307-330. pls. IgIo. 
Ss ERIKSSON, Be F. Zacu’s cytologische Untersuchungen iiber die Rostflecken 
des Getreides und die ae Sitzungsb. K. Akad. Wiss. Wien Math.- 
Naturw. KI. 119: pp. 
