218 THE AMERICAN NATURALIST. | (Vor. XXXIX. 
offers at once many interesting possibilities of explaining the 
close association of many cells and tissues, not alone in delicate 
dynamic interrelations but even in the exchange and distribution 
of food material and other products of metabolism. - It makes 
possible the conception of the plant body as a finely adjusted 
community of protoplasts intimately and sensitively related to a 
great degree in all parts, a view very different from the old idea 
of a cell republic. As might be expected, these speculative 
possibilities were conceived and expressed by such leaders as 
Hofmeister, Nägeli, Sachs, and Strasburger long before the 
detailed study of protoplasmic connections gave the mass of evi- 
dence upon which have been based the more elaborate concep- 
tions of recent years. 
The most obvious protoplasmic connections between cells may 
be found in the thallophytes where as in the Rhodophycee, 
Volvox, and in certain fungi, the cells in younger structures may 
be observed under comparatively low magnification to be united 
by strands of protoplasm so broad as to quite exclude them from 
the category of fibrille. Some of these structures are so con- 
spicuous that it is surprising that more was not made of them by 
early writers and that they have not been more extensively 
investigated recently. The greater part of the papers have 
been on the very difficult phase of the subject, the structure of 
pores and pits in the tissues of higher plants. The literature 
treating of protoplasmic connections is too extensive to be given 
detailed treatment in the compass of this paper. The best 
review of the subject is that of Strasburger (: o1), supplemented 
by the more recent paper of Kienitz-Gerloff (: 02). 
The earlier papers on the protoplasmic connections in higher 
plants, following the establishment of perforations of sieve-plates 
by Sachs and Hanstein, appeared during the years just preceding 
and following 1880. Thus Tangl ('79—81) described very clearly 
the communications between the endosperm cells of Strychnos 
nux vomica and Phoenix (see Fig. 16, a). Tangl noted the resem- 
blance of the complex of connecting threads to the arrangement 
of spindle fibers associated with the simultaneous division of the 
protoplasm in the endosperm but was cautious in assuming a 
relationship, suggesting that the resemblance might be super- 
ficial. 
