302 RESEARCHES ON FUNGI 



more or less independently of one another, as happens in Panaeolus 

 campanulatus, than when all are required to act synchronously. 

 An analogy may be drawn once more from the organisation of 

 an army. It is no difficult matter for a battalion of soldiers to 

 march in step and in proper order in ranks of four abreast, but it 

 would be less easy, were the ranks composed of 16 men. Now 

 imagine an army of 50,000 men all marching as massed formation 

 across a piece of country together. The order of march might 

 conceivably be 50 ranks of 1,000 men each, or it might be a parallel 

 series of battalions say of 1,000 men each in which there are only 

 4 men in each rank in each battalion. Even if the country passed 

 over were quite flat and presented no natural obstacles, with the 

 first arrangement, i.e. 1,000 men to a rank, it would be extremely 

 difficult for the ranks to be properly held. One part of a rank 

 would tend to bulge forward in front of other parts, and the most 

 exacting vigilance would be required by every soldier if the ranks 

 were to be kept anything like straight. A much easier way of 

 marching the army over the ground would be one commonly 

 employed and already mentioned, namely, forming the army into 

 battalions, arranging each battalion in a column-of-fours, and 

 marching the battalions massed together more or less in parallel 

 columns. Each battalion would have a certain amount of inde- 

 pendence, and every rank could be properly held. This second 

 method of organising the army is the one which is most nearly 

 analogous to the arrangement for bringing the basidia to maturity 

 in successive generations on a gill of Panaeolus campanulatus. 

 Each area roughly corresponds to a single battalion acting more 

 or less independently of its fellows. 



In concluding this section, I wish to call attention to the 

 interesting parallel which exists between the undulatory develop- 

 ment of the spore-producing hymenium of Panaeolus campanulatus 

 and the undulatory development of the epithelium which produces 

 spermatozoa in the testicular tubules of the Mammalia. When one 

 of these tubules, e.g. of a cat, is examined in a series of microtome 

 sections, waves of developmental activity can be traced along it. 1 



1 Cf. E. A. Schafer, The Essentials of Histology, ed. 10, London, 1916, 

 pp. 393, 395, Figs. 549, 552. 



