THE JOURNAL OF PHARMACOLOGY. 213 



of 4 to 6 angled, concave cells which are generally longer than broad, but 

 still almost isodiametrical. The side edge of the fiber is scarcely indented. 

 The edge of the epidermal cells is much thicker and very refractive. The 

 hair is somewhat thicker several centimeters above the base, the hair is 

 somewhat thicker and has conspicuously concave almost shell-like epi- 

 dermal cells, having a glossy edge. The medullary cylinder which has 

 been continuous up to this point now shows this peculiarity, that the 

 medulla disappears and the fiber gradually becomes but 35 p- in thickness 

 and assumes a structure which is just the opposite of the other course of 

 the fiber. Nowhere is it more fully illustrated than in this instance that 

 one and the same hair may microscopically assume structures at different 

 sections that are characteristic of other hairs. It lacks the medulla, the 

 fiber becomes uniformly thick and smoothly cylindrical and obtains very 

 transverse (horizontal) only 4 to 8 :>. high epidermal scales which are half 

 or apparently entirely cylindrical and imbricate. The regular fiber cells 

 impart to the fiber a beautiful straight striation. Two further character- 

 istics are found in this class. First here and there on the fiber we find a 

 longitudinal furrow. Then the medulla is not infrequently entirely ec- 

 centric so that it seems to be closely pushed to one side. Local swellings 

 and contractions also occur. The former occurs chiefly at the expense of 

 the at times very wide medullary cylinder ; wherever this is eccentric the 

 fiber as a rule is much thinner (40 to 50 m). It is also to be mentioned 

 that the outline of the medulla is often not well defined. The medullary 

 cells are generally elongated and are arranged in 2 to 4 rows, but it is dif- 

 ficult to distinguish them as such. 



The wool hairs are constructed somewhat more regularly, are about 10 

 cm. long and 35 to 40 p- thick, and are generally irregularly coarse curled, 

 without a medulla, with more horizontal low imbricated scales, which are 

 very thin, possessing an edge that may or may not be thickened. The 

 epidermal scales are half to entirely cylindrical. All transitional forms of 

 grannen and wool hairs are found in the Zackel wool. 



Ba7iat {e) Zigarra Wool (Fig. 6).— The following description proves 

 that there are some ordinary domestic wools that are almost without me- 

 dulla, that is have less on the average than the Leicester wools.* The 

 chief bulk of the examined sample consists of grannen hairs 30 to 70 /^ 

 thick. All the finer ones were entirely without a medulla, the coarser ones 

 partly so. Only a part of them contained medullary isles, which were 

 generally very narrow, almost linear and hardly visible. Larger isles 

 (which, like all the rest, always consisted of but one row) as well as longer 

 medullary strands were rare. 



The scales with generally thickened edges are broader transversely and 

 imbricate. Seldom arranged smoothly. The fibrous sheath is straight 



* Die Wohl von der Sudrussischen Zigaya zu unterscheiden ist. 



