PROF. B. GRASSI ON THE TCENIA NANA. 
505 
these taenia while some rats which were selected from the others 
and which were not fed remained uninfected. The large num- 
bers of taenia found (ordinarily there are but two or three) the 
young stages found corresponding in size with the time elapsed 
from the date of feeding, and the accuracy with which Prof. 
Grassi and his assistant S. Calandouccio have carried out and de 
tailed their experiments, preclude the possibility of error. He 
thus has proven that the development is direct and does not re¬ 
quire an intermediary host, as was formerly supposed. 
One or two of Stein’s cysticercus which have been described 
from meal-worms, and which have since been held to be the inter¬ 
mediary stage, were found and fed to a man but with no result. 
In dissecting a large number of these worms the author was 
forced to conclude that there was not sufficient cysticerci to ac¬ 
count for the abundance of taenia in the rats. In the light of 
Stein’s investigations, however, I think we should hesitate in ac¬ 
cepting the direct development of the eggs of T. murina as their 
only method of development, for it should be borne in mind that 
the cysticercal stage of taenia appears after all to be but a stage 
of arrested development. That these taenia could have these two 
methods of development seems, in the light of the present knowl¬ 
edge, to be the most plausible explanation of the phenomena pre¬ 
sented. 
Prof. Grassi identifies T. murina with T. nana on account of 
their strict anatomical resemblance, and makes a varietal differ¬ 
ence between them on account of the difference in size, T. murina 
varying between 10-12-20 mm. and T. nana between 33-35-40 
mm. The hooks of each are alike in size, form and numbers, (24 
-28). He describes an inconstant slight difference in the eggs. 
The importance of this identification, together with the life-history 
of T. murina and T. nana, has its bearing on the treatment of human 
patients infected with this parasite. 
Helminthologists will not be slow to substantiate or disprove 
the accuracy of these observations, and to experiment with other 
species. Now that another line of experimentation has been 
entered upon we may expect that our knowledge of this interest-’ 
jng class of parasites will soon increase, 
