3S 



HARDWICKE'S SCIENCE- GOSSIP. 



sperm-cells of the Hydra,* and also, like them, this 

 capsule opened and discharged therefrom a vast 

 number of those bodies into the surrounding water 

 (fig. 10, i"). Their movements in the water, and their 

 apparent size, were very similar to those of the 

 Hydra.f After the rupture of the capsule, and dis- 

 charge of the spermatozoa, that portion of the 

 globe became flattened or indented (fig. 17, K), over 

 andaround which were seen theescapedspermatozoa,J 

 that continued to float round the now transparent 

 globe, which soon again resumed the perfect round 

 form, and gradually the whole became quite opaque 

 and of a uniform granular appearance (fig. 18). Soon 

 there were some darker spots discernible within, 

 which gradually enlarged and became thicker; and 

 in about twenty-four hours these spots assumed an 

 oval form (fig. 18, L), each surrounded by a lighter 

 margin. These ovules vary in number from two to 

 six in different individuals, and continue to darken 

 in colour, and change in form, until they become 

 perfectly globular (fig. 19). At the same time the 

 dark part which had surrounded them now entirely 

 disappears, and they were enclosed in a perfectly 

 transparent envelope. So transparent was it, that 

 •at first it could be discerned only when a particular 

 ray of light was thrown upon it, when from its own 

 reflection it became visible ; but, in consequence 

 of its gelatinous nature, it was soon detected 

 through the many extraneous substances that came 

 in contact with and adhered to it ; such as decaying 

 vegetable matter, algaj, various Desmids, &c, with 

 which, long before their development, the eggs be- 

 came almost hidden from view. By this envelope the 

 eggs were evidently fixed in one place on the glass ; 

 in this state they continued for more than two 

 months, manifesting outwardly no perceptible 

 change. They were quite opaque, and had a fine 

 granular appearance. By Aug. 14 the envelope 

 had become of a darker colour, and was evidently 

 decaying away, and the eggs in some of them had 

 moved nearer the edge, and were observed slowly 

 to change their position. Aug. 29th two of the eggs 

 were clear of the envelope, so that the changes 

 that took place were distinctly seen (fig. 20). At 

 the end of about ten weeks from the time that the 

 eggs were fully formed, a contraction of the con- 

 tents took place, and a narrow line became visible 

 within the circle at the edge, which gradually 

 became broader and somewhat irregular as the con- 

 traction went on, until they had the appearance 

 shown at fig. 20. At this stage very slow movements 



* See Sciexce-Gossip, 1874, p. 1S8, and 1873, pp. 12, 13. 



t Those of the Hydra Professor Gulliver examined under a 

 high power, and proved them to be spermatozoa, estimating 

 the mean length of each spermatozoon at about 5-j 1 ^ of an 

 inch ; and could I have procured those thrown out of A. 

 Eichhomii, no doubt but he would have been able to prove 

 them of the same nature. 



X I call it spermatozoa, believing it to he so. 



were seen in the granular contents of the eggs. Dp 

 to this time no change had taken place in the size 

 of the eggs. On Sept. 11th, I observed that the 

 original circle of the egg was gradually expanding, 

 leaving a wia'er margin (fig. 21, S). This was at 

 twelve o'clock at noon; there were then no spines 

 visible; but in ten minutes from this time a very 

 delicate mantle, or envelope, was gradually thrown 

 out with an undulating motion round the egg 

 (fig. 21,0). In another ten minutes the envelope 

 was further expanded, and then could be discerned 

 very fine spines ai'ising from the now expanding 

 outer circle, but still within the delicate and newly- 

 formed envelope. The spines were in a somewhat 

 bent position at first, as though the envelope had 

 not extended far enough to allow them to push out 

 quite straight (fig. 21, P). The contractile vesicle, so 

 very characteristic of these animals, was now for 

 the first time seen in full action at this early stage 

 of development (fig. 21, R). The expansion of the 

 pellucid envelope continued to go on as the spines 

 increased in length. At the expiration of another 

 ten minutes they presented the form of fig. 22, the 

 undulating envelope still extending, and the spines 

 now pushed out very fast, both in number and 

 length, when the envelope suddenly collapsed and 

 disappeared altogether, and the spines rapidly 

 acquired their proper form and full length. In 

 about forty minutes from the commencement of the 

 enlarging of the original circle of the egg, the 

 Actinophrys was rendered perfect (fig. 21), exactly 

 like the original, but much smaller. In about 

 three or four days they increased to the full size, 

 when they measured about ^th of an inch in 

 diameter ; the egg measured about 3 ioth of an inch 

 in diameter. 



One of the young, the development of which I 

 had followed from the enlargement of the egg to its 

 perfect form, came in contact with the extended 

 spines of a large one, was speedily drawn to the 

 surface, and incepted like other particles of food. 

 The little fellow was soon dissolved, and lost sight of. 

 This did not look like the process of conjugation, 

 but rather more like cannibalism. At the same time 

 in the old one there were three vacuoles containing 

 food (fig. 13, C). Small particles taken as food glide 

 slowly down the tentacles; when the surface is 

 reached it becomes indented, and the spines cross 

 each other (fig. 13, A). As the food proceeds towards 

 the centre of the body, it becomes inclosed in sepa- 

 rate vacuoles, undergoing the process of digestion ; 

 the indented edge again resumes its usual form, and 

 the spines again become straight. 



At times there are to be seen, confined to certain 

 localities in the A. Eichhomii, granules in constant 

 motion, very similar to those always found in the 

 points of Clostcrium lunula, styled circulation ; but 

 these are not to be confounded with the spermatozoa 

 seen in the capsule, as the granules are much larger, 



