OF THE PHYTOZOA. 191 



Euglena to which it belongs. Thus, in E. acus it is long and cylindrical ; in 

 E. viridis, oblong and compressed ; and in Crumenula texta and Phacus, cir- 

 cular and compressed. 



There is yet another set of structures pointed out by Mr. Carter, deve- 

 loped from the nucleus, to which he assigns the nature of spermatozoids, 

 or male reproductive particles. " In Astasia/' he writes (p. 227), " irregular 

 botryoidal masses, dividing up into spherical cells, colourless and translu- 

 cent, or of a faint opaque yellow tint, present themselves so frequently (and 

 generally inversely developed with the o\ailes, as in the Rhizopoda), that I 

 cannot help tliinking that they are also developments from the nucleus ; but, 

 from not having seen them present that evident granular aspect which 

 characterizes this development in the Rliizojipoda, I have not been able to 

 determine satisfactorily whether they are parts of the latter, or that kind of 

 division of the sarcode into green spherical cells which sometimes takes place 

 in Efglena. 



" In Euglena, also, I have described a development of the nucleus partly 

 imder the idea that it might be a parasitic Ehizopodous develojmient ; but 

 now it appears to me a simple enlargement, granulation, and segmental de- 

 velopment of this body into polymorphic, reptant, mucous cells filled with 



spermatozoid granules, as in EMzojJods I have never been able to see 



the nucleus and its capsule in their original form when the spermatozoid 

 mass has been present, though I have occasionally in Amoeba, and almost 

 always in Euglypha, seen the empty globular capsule in connexion vrith the 

 latter." 



The contents of Astasicm, even of the same individual, are subject to great 

 variations in colour, distribution, and other characters, induced by age, the 

 action of the reproductive processes, and the influence of external conditions. 

 Thus, Perty tells us (p. 57) Phacus pUuronectes is at times filled with a 

 homogeneous green mass, at others has a large, round, central spot (vacuole 

 or nucleus ?), at others a large, clear space in the middle, having a central 

 dark nucleus ; and at others, again, the contained endochrome forms three or 

 four segments, each exhibiting many dark green nuclei. In Euglena vhndis 

 and E. Acus the contents become resolved into a formless mass, or into a 

 heap of nearly equal-sized germ-cells, and frequently the colour is changed 

 from green to red, or the whole organism is rendered hyaline by the escape 

 of the coloiuing matter. 



The colom-ed speck in Euglena, AmhlyopMs, and other Astasioia, reckoned 

 as an eye by Ehrenberg, has in fact no pretensions to that character. We 

 have pointed out that similar specks occur in Volvox and other generally 

 recognized plants, in all probabihty precisely similar to and stnicturally the 

 same as those of Astasicm. Sometimes in Euglena the red is diifased over 

 the entire body, as Cohn represents to occur in Sj^hceroplea annulina {A.N.H. 

 1856, xviii. p. 83), in small globules, which have the physical and chemical 

 relations of oil. In other instances, and occasionally in very young forms, 

 the red stigma is altogether absent. In Phacus pleuronectes, Perty states, 

 one speck is placed close behind another with an intermediate band uniting 

 them. Often in Euglence, instead of one stigma, two or more red granules 

 occiu', whilst in Euglena cleses the pigment-mass is quite irregular. In Cru- 

 menula the red spot is comparatively Yery large, and rests in the form of a 

 small obtuse cone upon the contractile vesicle. 



'' The eye-speck oi Euglena viridis,''^ says Perty (p. 117), " is round or oval, 

 and exhibits an elliptic or spherical vesicle, within which the colouring matter 

 is contained, smTounded by a more or less comi)lete brownish-black ring : at a 

 subsequent period the colouring matter is diffused in a most irregular manner 



