40 M. H. de Lacaze-Duthiers on the Development 



Science does not possess any extensive and connected work 

 on the embiyogeny of the polyparian polypes. Nearly all 

 authors whose object has been the investigation of the mode 

 of growth of the polypary have taken on the one hand the 

 calices or polyparites which appeared to be youngest, and on 

 the other those which seemed to be most completely developed, 

 and then, by seeking the tenns intermediate between these 

 extremes, have endeavoured to deduce, from the gradual 

 passage from the former to the latter, the laws either of the 

 multiplication of parts or of the general mode of growth of the 

 calices. 



We do not find zoologists attempting to recognize the first 

 traces of calcareous deposits in the bodies of the polypes while 

 still in the state of embryos, and to follow these first inorganic 

 nodules up to the complete formation of the calice or polyparite 

 with all its elements. In a word, they have almost exclusively 

 studied the isolated skeleton of the animal, or the polypary 

 itself. 



Laios, which we find prevailing in science, have been deduced, 

 not from the study of the framework during its formation in the 

 emhryo, hut from the observation of the formed polyparites of 

 different dimensions. In other words, zoologists have thought 

 that they could afirm what must have been from what ivas at 

 the moment of observation. 



In a polyparite (that is to say, in one of the calices of the 

 polypary of an Actiniarian of whatever species) it is well known 

 that there are radiating laminaj of various sizes. These 

 laminge of the first, second, third, to nth. size alternate regularly 

 in a certain order. The totality of those which are homologous 

 or similar constitutes what is called a cycle. Seeing this, the 

 same thought comes naturally to the mind of every observer ; 

 and it may be said that, in everybody's opinion, the equal 

 laminae forming a cycle are produced at the same period — that 

 they commenced and continued growing simultaneously, which 

 would explain their equality — and, finally, that the laminae of 

 difterent sizes are also of different ages, and that their extent 

 is in direct proportion to the duration of their growth (that 

 is to say, their age). 



It may certainly be affirmed that this idea, which occurs 

 naturally to the mind, has been the starting-point of the 

 numerous laws formulated from the examination of specimens 

 in collections — laws which have furnished the principal foun- 

 dation for the classifications and for the nomenclature of the 

 parts of polyparies, proposed especially by French authors. 

 Certain German naturalists, particularly MM. Schneider and 

 Rotteken on the one hand and C. Semper on the other, taking 



