Chap. IV. PARYPHA CROCEA. 263 



is reduced more than one half. We have here the most indisputable evidence 

 that each individual cell elongates or shortens, and narrows or broadens according 

 to the contraction or extension of the stem. We have seen this process repeatedly 

 while the stem was under the microscope, and have even observed a single cell 

 expand and contract quite independently of those around it; any one who will 

 make a transverse section of the stem, and watch the movements of the cells on 

 the edge [Fig. 7, g^) of any one of the broad semi-partitions which extend a\ong 

 the chymiferous channel, may test the truth of this statement for himself. Some- 

 times a single cell expands until it nearly reaches the centre of the chymiferous 

 channel; and so thin does its wall become at the time, that it could very easily 

 be overlooked. The cells which enter into the composition of these semi-partitions 

 {Fig. 5, g^), may be very readily seen directly through the outer {^ i^) and the 

 inner {g g^ g^) walls, and are distinguishable from the cells of the latter by their 

 relative position and their superior size. They are intimately united to the inner 

 wall, of which they are, in fact, centripetal prolongations, as a transverse section 

 {Fig. 7, g^ g*) shows. They are disposed in at least two layers {Fig. 7, g^ g*), 

 the inner one {g^) of which is narrower when the partitions are not expanded. 

 The brownish-red granular substance {Fig. 7, /) which lines the surface of the 

 chymiferous cavity of the stem, does not appear to be at all cellular in its nature, 

 but, rather, concretionary. The granules are more or less angulai-, and of all sizes, 

 from mere specks to apparently one sixteenth of an inch in diameter, as seen with 

 a magnifying power of five hundred diameters. Those in the immediate neighbor- 

 hood of the wall cling quite closely to it, but toward the centre of the cavity 

 they are in constant agitation, and, frequently detaching themselves from their bed, 

 rush along in the passing chymiferous current. 



The cells, which constitute the outer and inner walls of the peduncles (PI. 23, 

 Figs. 18, 18*, 19, and 19") of the medusoid bunches, have a close resemblance to 

 those Avhich we have just described, in the walls of the stem, but the former 

 are much smaller. The cells of the outer wall {Fig. 19% a) cannot be seen unless 

 the peduncle is contracted, because, when it is stretched out, this wall becomes 

 excessively transparent and quite thin. These cells, when seen with a magnifying 

 power of three hundred diameters, appear, in profile, to be about as broad as long, 

 with rounded exterior and flattened or truncate interior ends. When the peduncle 

 is stretched, all that can be seen of organization in this wall, are a few scattered 

 lasso-cells {Figs. 18, 18% and 19), which give it a spotted appearance. The cells 

 of the inner wall {Figs. 18, 18% 19, and 19% h), when the latter is in a strongly 

 contracted state {Fig. 19% b), are three times as long as broad, and are rounded 

 at the outer as well as at the inner ends. In this state the wall is very thick, 

 and yet it is composed of but one layer of cells arranged so as to give it a 



