367 



THE BIOLOGY OF THE PROPAGATIVE BUDS OF 



MALAX IS PAL UDOSA. 



WILFRID ROBINSON, 

 Hull. 



(plate XLI.). 



EvERYOXE who has gathered or observed Malaxis pahtdosa, 

 the smallest of our British orchids, must have been struck by 

 the singular appearance of the leaves which bear on and near 

 their margin towards the apex tiny swollen bodies, which, on 

 examination by reflected light, under a low power microscope 

 have the appearance of buds (fig. 2 h). The position of these, 

 in itself an unusual one for such bodies, together with the idea 

 of obtaining some knowledge of the facts of their structure and 

 development, and a better understanding of their true morpho- 

 logical nature and biological value, suggested the present study. 



The material used I gathered from three separate stations, 

 all peaty sphagnum runnels, near Killin (Perthshire) , in August 

 of the present year. It was killed and fixed in the field, em- 

 bedded in paraffin, and sections were stained with Benda's 

 iron haematoxylin. 



The buds (fig. 2) already referred to, have been variously 

 described. For example, Smith (c), in describing the drawings 

 for Enghsh Botany (Sowerby), says : ' Leaves should be a little 

 rough at the tip, as I have done them — they are minute teeth, 

 not hairs.' But for many years it has been recognised they are 

 of the nature of buds and their function, that of vegetative 

 propagation. When in a fairly advanced state of development, 

 I found them to consist, as Kerner [a), states, of an outer large- 

 celled envelope, which encloses a more compact central body, 

 In median longitudinal section (fig. 4) , the envelope is seen to be 

 of two to four cells in thickness, and arches over or completely 

 encloses the rounded interior body. This latter in the earliest 

 stages (fig. 5) to be seen in my preparations, I found was made 

 up of about four axial rows of very regular cells, much smaller 

 than those of the outer envelope, and with large nuclei, each of 

 which showed a distinct nucleolus. The next stage (fig. 6), 

 shewed towards the upper portion of this central mass, some of 

 the cells in active division ; and, owing to the greater growth 

 of the middle portion, the body had now assumed a more or 

 less rounded upper portion, with a basal region of four to six- 

 teen cells. These did not seem to manifest the same meris- 

 tematic activity as the upper portion. The exact shape about 

 this stage seemed to be somewhat variable, and the interior 



908 October i. 



