PROF.. AASSiarS 



those hairs arising from definite parts, or the 

 brashes may not arise immediately from the rings 

 of the animal, but there maybe vesictes into which 

 the blood-vessels may run, and from which arise 

 various hairs. And the manner in whieh these 

 hairs are combined with the vesicles, aad the ves- 

 sels and the little hooks which may be appended 

 to them, will constitute the most complicated ap- 

 pendages which can be imagined. 



And, indeed, there are no animals in whieh the 

 appendages are so complicated as they are observ- 

 ed to be in some of the Anaulata. The anterior 

 part may have one kind, the middle part m&y 

 have another kind, the posterior past may 

 have a third kind; or those of the head may 

 be very prominent, and those of the pos- 

 terior extremity of the body may be scareely dis- 

 tinct. And these are the more remarkable, as we 

 may find in the earlier condition of those aaJraals 

 that they are uniform. For instance, in this worm, 

 (Plate XXVIII, A) which is a new genus, whieh I 

 have called Pleigopththalmus, we have little brush- 

 es of stiff hair, and what is still more curioas, a 

 pair of eyes to each rJng, And when the animal 

 grows larger and larger these eyes vanish succes- 

 sively and there is only one pair left in the anterior 

 portion of the body, and one on the posterior part 

 of the body, and the intermediate ones are ^ one. 



And here (Cirrhatulas, Plate XXVIII, fig. B) 

 are not merely eyes, but several colored dots to 

 each ring, and along the whole body uniform vas- 

 cular threads. Eyes which have a crystaline 

 lens may gradually be found to pass to simple co- 

 lored dots. This is the case, foy instance, in the 

 Planaria (Plate XXIX, fig. E), where we have no 

 longer an eye, but we have a great accumulation 

 of black dots pon the skin, some of which are 

 larger than others, which can no longer be consid- 

 ered as eyes which can no longer be considered 

 as organs of sight but which are doubtless an ap- 

 paratus simply to receive an impression of the 

 light. 



These animals, without eyes properly, but simply 

 with colored dots, must have merely impressions 

 of light. The eyes are merely to concentrate the 

 light. In Cirrhatulus, we have simple vascular 

 threads (Plate XXVIII, fig. b> to each ring ; but in 

 Terebella, which is the perfect state of the same 

 animal (Plate XXVIII, fig. C< they are reduced to 

 complicated gills behind the head. The vessels of 

 the anterior gills, which occur in the anterior part 

 of the body are indeed only modifications of these 

 vascular threads. In the young animal (Plate 

 XXVIII, fig. B), which has been described as a pe- 

 culiar animal, under the name of Cirrhatulus, we 

 have the threads all along the body, and the pos- 

 terior threads, gradually disappear first, and the 

 anterior ones are branched and transformed into 

 gills ; and in the beginning there are vascular 

 threads, one to each ring. 



Let me now add another fact referring to this 

 animal, that this Cirrhatulus, when young, as it is 



represented here (Plate XXVIII, fig. B / is 

 resceat. The adult, which has been described as a 

 Tersebella, is also phosphorescent. But in the last, 

 phosphorescence is only noticed in the long 

 threaelSjbutin Cirrhatmlus it is noticed all along the 

 body. On close examination I have satisfied my- 

 self that the blood vessels are the pborphorescent 

 apparatus. Some such threads separated from 

 the bedy when acted upoa by alcohol, or some 

 other strong reagent, would throw oat faint light 

 when no other part of the aaimal would emit 

 it. So that we have here an example of phos- 

 phorescence in a position of the body different 

 from another whieh we have mentioned before 

 This phosphorescence proceeds from the blood 

 vessels. We have had aa exam-pie from the ner- 

 vous system* I may Quote others ; for instance, 

 some Insects in whieh the respiratory organs, those- 

 Traeheal organs, those aerial sacs, will emit 

 light; and tbe focts are such that we perceive a 

 connection between coloration and phosphoresenee 

 and sight, as tfoere is between electricity, heat and 

 light. The physical phenomena are parallel to the 

 phenomena in the animal kingdom, only it is more 

 difficult to show their connection ; but I hope to 

 show that there are at least among the Mollusca v 

 some types in which it may be demonstrated that 

 euch a connection exists. 



[PLATE XXXV CATERPILLAR.! 



L.C. im- aud one more )etnark, thai the Ca,ierpil- 

 lar, with all its appendages, (Plate XXXV) should 

 be eomjmyea! with the Worms. "What are the di- 

 versified hairs which are observed upon so many 

 Caterpillars 1 They have been usually considered 

 as hairs; but they are connected with the organs 

 of locomotion and respiration, as in the Annulata. 

 We should, therefore, institute upon the Caterpil- 

 lar a regular comparison, to ascertain whether they 

 are not in some respects analogous to the various 

 appendages of the Worms. This comparison I 

 have not instituted. It remains to be done ; but I 

 cannot he)p thinking, on noticing the close resem- 

 blance there is between the diversified aspect of 

 Caterpillars and Worms, that in their analogies 

 there will be also a type discovered, as it. has been 

 noticed in the appendages of Worms ; and thas 

 Caterpillars will only be another modification more, 

 of one and the same type. 



[PLATE XXXVI SYMBOLICAL FORMULA OF AR- 

 TICULATA ] 



