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also the yolk membrane terminated. Thus the lateral tubes of 

 the egg, as well as the balls in which they terminated, are to be 

 considered merely as excrescences and appendages of the outer 

 (the third) coating of the egg. Similar appendages to the eggs of 

 tapeworms have been met with previously by other observers ; 

 namely, threads running out on two sides in Tcenia wfandibuli- 

 formis and plaiiiceps by Von Siebold, (1. c. p. 148,) and Tcenia 

 cyathiformis by Dujardin, (1. c. p. 568, and figured PI. 9, Fig. 

 R. 2,) while Von Siebold (1. c.) describes the eggs of the same 

 worm as provided at the pointed ends of their outer pear-shaped 

 coatings, with two bladder-like appendages, which remind one 

 more of the new form just described. Two delicate tufts, one on 

 each side, have been observed by Meissner in Mermis nigres- 

 cens (Beitraegc zur Anatomie und Physiologie der Gordiaceen, 

 in Von Siebold and Kolliker's Geitschrift fur Wiss. Zool. VII. 

 Taf. II., Fig. II.) and by Siebold, 1. c. in Tcenia variabilis. All 

 these appendages belong to the third coating of the egg, adjoining 

 the so-called chorion. Analogous appendages are found in the eggs 

 of sharks and skates. Some of the embryos were hatched under 

 my eyes, and, in spite of the greatly different organization of the 

 adult worms, their organization was seen to be throughout identical 

 with that of the embryos of the genuine Ta^nias, (those of man, dog, 

 cat, etc.) namely, a roundish disk, containing smaller and larger 

 granules, and provided with six little spines, disposed in three 

 pairs, two lateral and one in front. We might ask here, is it 

 only the simplicity of organization which causes this similarity of 

 such incipient organisms, which are so distant from each other 

 when adults ? or is it perhaps rather the real and material ex- 

 pression of the ideal unity of such a type (that of Ttenioids, for 

 instance) ? The embryos of all Dicotyledonous plants start with 

 a little root and two leaflets, whatever difference they may ex- 

 hibit, when full grown, in relation to the organs of nutrition, 

 respiration, or reproduction ; they may have the complicated 

 flowering of a rose, or the simple perigon of an oak. Thus every 

 Dicotyledonous embryo exhibits materially the unity of that great 

 diversified type. Again the simple cell, from which both ani- 

 mals and plants originate, represents materially that j^deal unity 

 which embraces all living beings. If this be so, the question 

 arises, can we extend this principle, which has already laid open 



