Evidence from Somatic Histogenesis 



55 



as it almost certainh' will be, that Hic cjto])lasni is "hered- 

 itary substance" for the production of s])iciih's, tlic reverse 

 of Conklln's generalization that the cytophism dctcrniiues 

 the larger taxonomic features of animals while chromatin is 

 the seat of the inheritance factors for "fillinir in details" 

 turns out to be true. Species-marking details arc just 

 what we are able to see the cytoplasm fill in. 



The "Hairs'' of Higher Plants 



For a few more instances of species characters in multi- 

 cellular organisms brought down to single cells, we turn to 

 the plant world. 



FIGURE 5-2. FIGURE 53. FIGURE 54-. 



FIGURE 52. TRICHOIMES OF PAPAVER ORIENTAI.E (aFTER CANNON ). 

 FIGURE 53, TRICIIOMES OF P. PILOSUM ( AFTER CANNON ). 

 FIGURE 54. TRICIIOMES OF P. SO^IXIFEHr^I (.MTrH CAN SOS ). 



The "hairs" or trichomes borne on the leaves, flowers 

 and smaller stems of innumerable flowering plants are 

 usually composed of only a few cells, so that the characters 

 they have are often referable to the individual cells. Can- 

 non has lately investigated these structures in several gr()U])s 

 of plants, and while he was not aiming at the particular 

 question now occupying us, some of his results are (jiiife to 

 the point for this discussion. An exami)le of particularly 

 distinct specificity of the hairs Is ])resented in the following: 

 "The trichomes of the three species | of p<>pi)y | are similar 



