244 



SCIENCE-GOSSIP. 



[Nov. 1, 1865. 



A CHAPTEH FROM THE LIFE OE 

 A VOLYOX. 



DROP of water is a world to the minute 

 beings that inhabit it. We place it under 

 the microscope, and are astonished to find that it is 

 a world teeming with life, and that the forms of 

 life are not less beraitiful and scarcely less varied 

 than those of the higher beings that dwell in the 

 great world around us, and therein exercise their 

 wonderful instincts. 



There are various instincts at work amongst the 

 tiny inhabitants of that little world, though, on 

 account of the apparent simplicity of their structure, 

 we are often inclined to think their actions more the 

 result of mechanical than of instinctive power, 

 perhaps only because our microscopes are not even 

 yet perfect enough to reveal all the complexity which 

 really exists. 



I once had the good fortune to observe an 

 incident, which I do not think has ever been, 

 recorded before, in which two of the inliabitants 

 of a drop of water — the Rotifer and the Volvox — 

 played a very curious part. Whether what I saw 

 was the result of instinct, as I would fain believe, 

 or whether it was mere caprice or a chance action, 

 I must leave my readers to judge for themselves. 



All who read Science Gossip do not profess to 

 be learned naturalists, and they wiU perhaps like to 

 know what sort of creatures these Rotifers and 

 Volvoces are. The first is undoubtedly an animal, 

 and one of the most active that you vviil find in a 

 drop of water ; darting about here and there, poking 

 his nose into every corner, rolling about like a 

 porpoise, and, Proteus-like, assuming various forms. 

 He is put by naturalists into the lowest division of 

 the animal kingdom,— the division i^tffZ/Vi'fe ; and, by 

 some, into the lowest class of that division,— the 

 class Lifusoria^ which consists entirely of minute 

 animalcules, some of which are so low in the scale 

 of creation as to have only one organ, and that a 

 stomach; the whole animal, in fact, being a stomach, 

 with an opening at one end for a mouth, and some- 

 times not even that. 



The Infusoria, however, are not all of them of 

 quite so simple a structure as this; and amongst 

 them are a number of species of our friends the 

 Rotifer?, so called because around their mouth they 

 have two or more sets of cilia or hairs placed in 

 circles, and which, being in constant motion, have 

 the appearance of revolving wheels. They have the 

 power of stretching themselves out and retracting 

 like worms ; and their tail acts as a claw, by which 

 they can anchor themselves to a leaf or anything 

 in the water; and they can likewise draw in their 



wheels at pleasure. Under the microscope there is 

 seen, within their transparent bodies, a complicated 

 arrangement of digestive organs. Here is a drawing 

 of one of the Rotifers. 



* Otiiers place the Rotilers hi the class Annelida; others 

 agahi in the class Crmt tcete. 



Tig. 1. Rotifer vulgaris. 



The Volvox is a very different object. It is just 

 large enough to be seen with the naked eye, when 

 the water containing it is held up to the light, and 

 appears like a green speck floating in the water ; 

 indeed, after some practice in looking for minute 

 objects, it is possible to fish a single one out of a 

 wine-glassful of water with a teaspoon. A low 

 power of the microscope is sufficient to reveal one 

 of the most beautiful objects that it is possible 

 to conceive, — a globe of the most delicate green- 

 colour, formed of a transparent membrane, which is 

 marked with a network of fine lines, with darker 

 green spots where the lines cross. Within are seen, 

 smaller A^olvoces precisely similar to the parent, and 

 sometimes within these, smaller ones still. The 



ftx^ 



Fig. 2. Volvox globator, 



Volvox, by means of a constant rolling motion, 

 moves slowly through the water from place to pkce. 

 When viewed with a higher power, the green spots 

 are found to be bunches of delicate hairs, and prot 

 bably the constant motion of these propels the 

 Volvox through the water. 



