Anatomy and Histology. 97 



plasts, few in number, however, are present in the cortical cells. The 

 endodermis is well marked and contains a good many large starch grains. 

 The Casparian spots are readily recognized. 



The stele (0.18 mm. in diameter in a hypocotyl 0.53 mm. in diameter) 

 is, at an early age, tetrarch above the zone of transition to the root. The 

 four bundles are received into the hypocotyl in pairs, one pair from each 

 cotyledon, in which they constitute the median trace. After reaching the 

 lower part of the lamina they unite, as they do in the lower part of the 

 hypocotyl (in the "collet"), to form a single bundle. 



In addition to the median paired cotyledonary traces, there are 

 delivered into the hypocotyl four lateral traces which meet in pairs to 

 constitute two bundles which pass inward and downward. Each takes a 

 position, the one on one side of the stele, the other on the other, in a ver- 

 tical plane at right angles to that which divides both cotyledons. They 

 are the " faisceaux lateYaux " of Dangeard (1889, p. 85). So far, then, this 

 plant satisfies the "cas secondaire" of his root type with two bundles, 

 found in the Compositae and certain Ranunculaceae. According to Dan- 

 geard, however, the behavior of these bundles is, to use his own words, 

 as follows: "Les premiers (f. median) se comportent comme dans le cas 

 general; 1 les lateraux s'anastomosent plus ou moins longuement avant de 

 rejoindre le median vers le bas." 



If I interpret Dangeard's statement correctly, we should find that 

 the lateral traces (plate 24, figs. 2 to 5, 12) anastomose with the median. 

 This, however, I do not believe to be the case. By following the figures it 

 will be seen that the lateral traces are to be seen in the upper part of the 

 hypocotyl, but end rather soon. The broad medullary ray between the 

 pairs of median bundles is then unoccupied, and remains so till the cauline 

 bundles encroach upon it. Between these cauline bundles, at the proper 

 level, the slender end of the lateral cotyledonary trace may be seen, quite 

 single and separate from them (plate 25^ fig. 10). In the diagram (plate 

 24, fig. 13) the fused lateral traces are represented as being much shorter 

 than in that given by Dangeard for Catananche lutea. 



In types with a tetrarch root-structure this trace passes downward 

 and articulates directly with two of the primary hadrome strands. This, 

 e.g., occurs in Caulophyllum thalictroides (Butters, 1909) and in numerous 

 other plants cited by Dangeard (I.e.). 



The intervals between the lateral and median bundles are occupied 

 by two cauline traces, or, more properly speaking, by one (lateral pro- 

 phyllonary) and a half (of the corresponding median prophyllonary) 

 traces. There thus appear in the higher levels of the hypocotyl: 



(1) 8 cotyledonary traces, viz, 2 pairs of half -median traces; 2 pairs 

 of lateral traces. 



(2) 8 prophyllonary traces, viz, 4 half-traces, a half-trace on each 

 side of the cotyledonary laterals; 4 lateral traces, one on each side of the 

 cotyledonary median pairs. 



Passing down, the i cauline bundles in each cotyledonary median- 

 lateral interval fuse with each other and then with the adjacent median 

 trace. Below the level of this fusion the tetrarch structure is assumed, 



1 That is, as above described. 



