156 ON BIASTREPSIS IN ITS RELATION TO CULTIVATION. 



has so far been observed to extend over a larger or smaller area of 

 the main stem or of the branches. 



Individual variations are obtained pure from pure seed; the 

 conditions of germination and of subsequent cultivation have no 

 effect upon this. Hence their cultivation does not involve anything 

 more than that of the species to which they belong. However, it 

 often happens that the seed, obtained by exchange or by purchase, 

 is not quite pure and therefore selection by weeding out may have 

 to be exercised. Partial variations, on the other hand, depend almost 

 as much upon the cultivation as upon the seed. The purest seed is 

 no absolute guarantee for a satisfactory batch of seedlings, unless 

 the treatment has been appropriate. Then again, in the more fa- 

 miliar breeds, rarely more than one-third of the individuals exactly 

 reproduce the abnormality, the others reverting more or less com- 

 pletely to the type. 



With regard now to the raising of plants with partial variations. 

 The seed must, of course, be taken from those members of each 

 generation which show the abnormality (twisting, fasciation, etc.) 

 in the highest degree. The plants selected as seed-bearers must be 

 isolated before flowering, either by digging up all the rest or by 

 removing all their flower-buds. In their cultivation the following 

 points must be regarded. In the first place the sowing must be 

 made at the proper time, usually in April; it is best to sow in pans 

 under glass. The seedlings should be pricked out when they have 

 developed the second leaf and should either be planted out at once 

 in their ultimate position or be kept singly in pots for a few weeks 

 (pots of 8-10 cm., or .3 in., are the best). Further, most monstrous 

 plants require an open, sunny situation, plenty of space and much 

 manure. The attempt should not be made to grow the plants in a 

 shady place; sometimes it may be successful, but the result is very 

 uncertain. The plants should, from the very beginning, be planted 

 so far apart that they do not touch or overshadow each other at all, 

 or at least not until they have grown so far that the monstrosity 

 has made its appearance. The amount of manure required obviously 

 depends upon the nature of the soil, but it can hardly be given in 

 excess. I made use of dried cow-dung, so-called cattle-guano, and 

 horn-meal (crushed and steamed horns and hoofs) and gave l^-l 

 kilog. of this mixture to every square metre of soil. The seed-pans 

 must not be manured at all, otherwise Botrytis cinerea, the great 

 enemy of all special cultures, will be developed. 



I propose to describe now a series of experiments, all of which 



