THE INTESTINAL PROTOZOA OF FROGS AND TOADS. Boe 
filaments of spermatozoa.” My own interpretation, that the 
trichomonad blepharoplast and the end-knob (not in any way 
the karyosome, however) are homologous, seems to me to fit 
in with the facts much more satisfactorily. ; 
And this brings me to the point to which all the foregoing 
remarks are converging. In short, I believe that the divers 
structures with which we have been dealing—blepharoplast 
of fern, trypanosome and trichomonad, end-knob of sperm, 
and hence also centrosome—are all strictly homologous 
structures. That they are identical one cannot, of course, 
say. For the trypanosome blepharoplast is not, except in a 
very wide sense, a cytocentre. But functionally they are 
identical ; in each they give rise to the locomotor organs—tail 
filament, undulating membrane or flagella, cilia—of the cell 
to which they belong. And from their behaviour one would 
suppose that they not only give rise to these organs, but 
also remain to preside over their functioning after their 
formation. 
I do not wish to enter into a full discussion of this difficult 
matter here, so I will content myself with a very few further 
remarks. ‘To do justice to the subject one would have to 
review a greater mass of literature than there is room for in 
this paper—all the work, that is, dealing with the so-called 
Lenhossék-Henneguy hypothesis. 
When I mention the end-knob of the sperm and the ble- 
pharoplast of a fern or trypanosome as homologous, I do not 
mean to imply that similar organs in other organisms are not 
to be included in the same category. Indeed, I believe there 
are many other quite similar arrangements. It will suffice 
to recall the condition described by Ischikawa (61) in the 
spores of Noctiluca. ‘he centrosome is here seen to lie at 
the base of the flagellum, just like a blepharoplast. It is 
difficult to believe that it could be other than homologous. 
Further, the conditions described by Schaudinn in H 2mo- 
proteus noctue are not necessarily antagonistic to this 
hypothesis. Assuming that these unconfirmed observations 
of Schaudinn are correct, it does not follow that they apply 
