PANAEOLUS CAMPANULATUS 299 



be placed side by side in contact, as shown in Fig. 102 at B, they 

 would occupy an area which is roughly one and a half times the 

 original area. The impossibility of all the basidia on any area 

 successfully producing and liberating their spores at one and the 

 same time thus becomes obvious. The actual distribution of the 

 spores on the area A at any one time during the spore-discharge 

 period is indicated by the camera-lucida drawing reproduced in 

 Fig. 102 at C. If all the spores produced on A were to be developed 

 simultaneously and were to have the spacing shown at C, the area 

 A would need to be made about seven times as large as it 

 actually is. 



It is clear from the above discussion that the production of 

 successive generations of basidia enables a hymenium to produce 

 and successfully discharge many more spores than would be possible 

 if only one generation of spores were produced. Yet the further 

 question remains : why should the succession on any small area 

 take the form of successive generations of equal-aged or almost 

 equal-aged basidia ? The answer may be obtained, perhaps, by 

 comparing the basidia to soldiers. In order that a battalion shall 

 pass across a narrow piece of ground, along a road, or through 

 a pass, with the greatest speed and smoothness, it is organised 

 into a column of fours. The soldiers in each four march shoulder 

 to shoulder in step, and any one point on the line of march is passed 

 by four after four at successive intervals. Efficiency in passing 

 any given point in a given time by the whole force is only obtained 

 by giving to each soldier suitable space-relations with his fellows 

 in the same four and with those in the fours in front and behind. 

 If a battalion becomes disorganised, so that each man loses his 

 former space-relations with his fellows, it becomes reduced to a 

 crowd of men who are apt to impede each other's progress by getting 

 in each other's way. For the purpose of passing a given point 

 on a road of limited width in a given time by a large number of 

 men, the advantages of the column-of-fours arrangement over the 

 go-as-you-please arrangement are sufficiently well known from 

 experience. It seems to me probable, therefore, that the battalion 

 method of bringing the basidia to maturity on any small area of 

 the hymenium has come into existence in the course of evolution 



