264 The Unity of the Organism 



after pairing, two entirely different sets of ceremonies be- 

 ing involved in the activities. One of these Huxley calls 

 ceremonies of mutual display, the other, ceremonies of coi- 

 tion. The highly elaborate mutual display performances 

 are fully described but can not be reproduced here. They 

 consist in a variety of body attitudes, head and wing and 

 feather movements, swimmings and divings, and call-notes, 

 the w^hole lasting some minutes. Concerning this prelim- 

 inary operation, Huxley writes : 



"The most noticeable thing about all these ceremonies is 

 that they are 'self-exhausting' — they do not lead on to any- 

 thing further. Looked at from the physiological point of 

 view, they seem to me to be notliing but 'expressions of emo- 

 tion' : the birds act thus because they are impelled to do 

 so, because they enjoy it. Looked at, on the other hand, 

 from the evolutionary point of view, they seem to have been 

 developed as a bond to keep the pair together." ^^ 



Following these preliminaries, the ceremonies of coition 

 take place, these being less striking, though characteristic. 



Speaking of his studies on the mating habits of some of 

 the warblers, and referring to differences of interpretation 

 between himself and W. P. Pycraft, another observer in the 

 same field, Huxley writes : "In this, Mr. Pycraft and myself 

 are, I tliink, agreed; to both of us the 'display' of the male 

 Warbler is nothing but a direct expression of sexual excite- 

 ment, scarcely, if at all, modified by Darwinian Sexual Se- 

 lection — nothing but the way in which nervous disturbance 

 caused by sexual excitement happens to liberate itself. Gen- 

 eral nervous discharge will cause general muscular contrac- 

 tion ; and something approaching this is here seen — rapid 

 hopping, extension and fluttering of the wings, spreading 

 of the tail, bristling up of the fea.thers on head and 

 throat, and utterance of a series of quick sounds. This ex- 

 presses a condition of readiness to pair, and doubtless to 

 the female comes to be a symbol of the act of pairing. 



