No. 401.] REVIEWS OF RECENT LITERATURE. 435 
along as if carried by a current; that they are not in a current of 
protoplasm seems demonstrated, the author thinks, by the fact that 
granules pass in different directions close to one another, and one 
may even advance against the “stream” or crowd of others going 
in an opposite direction. "These same facts strengthen the author's 
belief that protoplasm is not a liquid. 
The author explains these apparently automatic movements of the 
granules (and of the chlorophyll bodies) as due to contractility, not 
resident in the granule but in the adjacent protoplasm. He adopts 
the inotogmata hypothesis of Engelmann, and conceives fibrils made 
of living particles emporarily joined. Along those transitory fibrils 
waves of contraction proceed, and thus the adjacent, inert, dead 
granules are, in some way, forced along. The granules are moved 
along in temporary routes made by the contractile fibrils. 
The basis for the assumption of such hypothetical fibrils is: (1) 
the existence of visible fibrils, (2) certain changes in optical value, 
and (3) waves of contraction seen under the microscope. The 
author agrees with Biitschli that the structure of the protoplasm in 
these cells is that of a foam; he sees striations and cross-connections 
in masses where shape and arrangement change in such wise that 
the existence of a foam seems to underlie the above appearances. 
But in the structure lines, lamellae he thinks them, he also sees 
long and short fibrils which are sometimes stationary, sometimes 
moving along like granules. These curious fibrils are soft and easily 
break up; they are, he maintains, in the walls of the alveoli, that is, 
between the vesicles of the foam structure. He supposes these 
fibrils are the remnants, or ruins, of hypothetical contractile lines of 
protoplasm which are no longer functional. 
The changes in optical value spoken of are passages from bright 
to dark which are seen in the lamellae, and interpreted as being 
coexistent with changes in the contractile material. 
The waves of contraction seen are bendings in the ww straight 
lamella, or striations. 
Whatever the nature of these remarkable cecal vaciar fibrils, their 
existence harmonizes the divergent views of Flemming and of 
Bütschli to the extent that a foam structure is found with actual 
fibrils between the alveoli; in this and in several other points the 
author's observations confirm some of the facts recorded for various 
animal cells by G. F. Andrews! and open a most suggestive field of 
research upon oft-tried material. E. A. A 
1 The Living Substance. Boston, Ginn & Company, 1897. 
