124 



HARDWICKE'S SCIENCE-GOSSIP. 



FERTILISATION OF ORCHIS MASCULA. 



By Edward Malan. 



[Continued front p. 102.] 



THE tubers, I believe, behave pretty much as I de- 

 scribed. Most of the plants that I have taken up 

 in April, have been about 2 inches below the surface. 

 In August it is exceedingly difficult to find the tubers, 

 as there is absolutely nothing above ground to assist 

 your search, and although I have frequently marked 

 the place and position of plants in April, yet I have 

 been disappointed when I returned four months later. 

 You may dig, and you may dig, but nothing will you 

 find. Why is this ? Clearly the tubers descend ; 

 and the reason of this descent is to prevent premature 

 germination, which, if allowed to proceed without 

 the proper interval of rest, considerably weakens the 

 plant of the following year. The case of the tuber 

 that I mentioned as being deeply planted, was an 

 experiment, and it was purposely prevented from 

 rising, by being kept at a uniform depth of 3 inches 

 below the surface. The result was very disastrous to 

 the plant, but the new tubers grew better when the 

 leaves were above ground. The drawings which I 

 made at the time can be seen. 



Lastly, as to the breaking of the stem affecting the 

 flower of the new tuber. Here G. M. has not 

 quoted my words correctly. Breaking the stem 

 certainly cripples the plant of the following year, and 

 prevents its flowering ; at least, I have only observed 

 one exception to this, and the notes that I made can 

 be had for the asking. But I did not say that I saw 

 a perfectly healthy plant minus its tubers : I said 

 tuber. This rather alters G. M.'s case against me. 



Now let me go out and select a plant of O. mascula 

 and let me explain what I mean. [One hour 

 occupied in finding a plant.] This one that I have 

 found (March 9th, 1885) will just do. Clear away 

 the soil carefully, and do not break a single root. 

 Then proceed to vivisect the victim. Just place 

 your knife, my classic Ajax, where it will cut 

 sharpest, and divide the plant in half, leaves, tubers 

 and all. There, the thing is done, and this drawing 

 is a faithful representation of the result. We will 

 call the left-hand tuber (i.e. the tuber of 1884-5) A ; 

 and we will call the right-hand tuber (i.e. the tuber 

 of 18S5-6) B; evidently the plant arises from A; 

 evidently B has no independent existence as yet. 

 Accordingly A answers to the old tuber of my 

 description, and B answers to the new. There can 

 be no mistake now. 



Last autumn, while men were slumbering and 

 sleeping and caring very little for this particular 

 tuber, the silent processes of life were at work, and 

 A took courage and started the thing going. First 

 of all the embryo, containing the leaves and spike, 

 germinated little by little, drawing upon A for its 

 resources, in this the first stage of its growth. The 

 embryo is now the plant on the table before me. 



How long A directly supplied the embryo I cannot 

 say for certain, as it appears to depend very much on 

 the moisture or dryness of the soil, but it cannot be 

 for long, for as soon as the roots appear, the 

 germination of the embryo is considerably ac- 

 celerated, and A hardly decreases in size at all, 

 afterwards. If you ask how I know, I reply because 

 I have been there to see. So far, then, my remark 



Fig. 85. — 0. mascula. a, Old tuber ; b, new tuber. 



about the tuber containing a store of food not for the 

 leaves and stem, is correct, I believe. The remainder 

 of the remark must be considered next. 



A glance at my drawing will show that the roots 

 supply the leaves directly, for otherwise why should 

 they not proceed from the base of the tuber ? and 

 the plant that I mentioned, minus the tuber, ought to 

 have been crippled or dead. But it wasn't. 

 Therefore my conclusion is that the leaves and 



