96 



LUCERNARI^ AND THEIR ALLIES. 



196. The ChomlromijopJax (^ 65-68) of the umbella. We have, on more than 

 one occasion, in various papers, urged the necessity of the closest and minutest, 

 critical observation of tlie details of all parts of the body of an animal ; leaving no 

 point untouched as if it were of too slight importance to deserve more than a pass- 

 in<^ notice, or as if it had no direct relation with the rest of the organization. 

 The piecemeal manner in which the anatomy of living beings is frequently 

 worked out, a few notes made here, and a few there, with no particular reference 

 to anything except to the novelty of the subject in the mind of the observer, has 

 no doubt led on to tlie meagre, scattered, and unsatisfactory results which lie hidden 

 in innumerable periodicals, journals, memoirs, and even the popular papers, week- 

 lies and dailies. One cannot sometimes help fancying that a large part of the so- 

 called facts of science are the result of the labors, or we might say the struggles, 

 of innumerable incompetents, who, like some of the inmates of an insane asylum, 

 dclidit in secreting valuables in out of the way places. The lower we descend 

 among the inferior ranks of animals the more directly do the histological elements 

 appear to be connected with the plan of their organization. No doubt this is 

 owing in a large measure to the want of diversity in the form of the organs and 

 their slight degree of differentiation for physiological or other purposes. In fact 

 we might venture to say that a differentiation of histological elements precedes 

 that of organs and regions. That this is most notably so, in some cases at least, 

 no one who is fi^mihar with the muscular system of Ctenophorse, and especially 

 with that of Pleurobrachia or Cydippe, need doubt. In these creatures the bulk 

 of the body is made up of a gclatiniform mass, which at first sight appears to be 

 homogeneous throughout. Closer scrutiny reveals the fact that it is not so, but 

 composed of two elements; the one a clear, transparent, homogeneous, all-per- 

 vading, jelly-like substance, and the other dispersed throughout the latter in Hie 

 form of innumerable, hyaline fibres. These fibres, however, are not scattered 

 irregularly here and there, but disposed in a most orderly and methodical manner; 

 yet still do not attain to the main essentiality of true differentiation, viz., segrega- 

 tion and concentration into a well defined organ ; but, on the contrary, the fibres 

 of one group thoroughly intermix with those of another, and cross and recross each 

 other without confusion. Thus, then, we see that a differentiation into contractile 

 and non-contractile tissue is decided, whilst a differentiation into distinct organs is 

 but half carried out — merely foreshadowed. The plan of the arrangement of the 

 fibres is inseparable from the plan of the arrangement of the (jroups which they 

 compose, and the first plan precedes the second. Such and similar considerations 

 have led us to give more than a passing glance at the disposition of the histologi- 

 cal elements of the gelatine-like mass of the body of Lucernariae. Not only do we 

 find in Hahclystus a muscular system developed to the highest degree among Aca- 

 lephse, but also the elements of the cliondrophijs and chondromyoplax arranged with 

 a greater preciseness and method than can be observed in any other order. It is 

 not a little remarkable, too, and as if confirmatory of the high rank which we claim 

 for Lucernaria;, that the arrangement of the fibrillse in the Ghoiulrophijs of the 

 peduncle recalls the disposition of those in the Ctenophorce, in spite of their clearly 

 diverse function. Looking at the choudronii/oplax from a pliysiological point of 



