22 THE BEGINNINGS OF LIFE. 



advances which the biological unit makes along the path which 

 leads to such bewildering complexity and to such a marvellous 

 phenomenon as conscious intelligence. With a few illustrations 

 in this direction I must occupy the remainder of my paper. We 

 saw in spirogyra that the cells adhered end to end so as to form 

 a filament ; but each cell is the counterpart of every other cell, 

 and if separated is perfectly able to lead an independent life. 

 There is no assumption by different cells of different functions — 

 no division of labour. A step higher we have colonies of cells. 

 You can often obtain a beautiful example of such a cell colony in 

 the ponds round Brisbane. If you obtain a bottle of water from 

 any of these you will not unlikely observe, on holding it up to 

 the light, a number of minute green globes, just visible to the 

 naked eye, rolling slowly and majestically onward, and at the 

 same time rotating on their axes. This is that favourite of 

 microscopists, the volvox globator. When one of these tiny 

 globules is examined with a low power it looks like a light green 

 pellucid net dotted regularly with minute green spots, and 

 generally having within it from two to eight smaller spheres. 

 When each of the spots is examined more carefully, and with a 

 higher power, it is found to be a cell — a speck of protoplasm, 

 furnished with two long processes or fiagella, just like the active 

 form of protococcus, of which you saw a diagram earlier this 

 evening. Although the appearance of the volvox is that of a net, 

 there are no interstices or gaps in the surface of the sphere, for 

 each cell is connected with the cells around it by means of its 

 hyaline envelope. The green bodies in the centre of the net are 

 young volvoces, which have been formed from enlargements of 

 the ordinary cells, and when sufficiently developed have detached 

 themselves internally, remaining in the parent sphere until it 

 finally bursts and they swim forth. Before this happens you 

 may often see them revolving by the action of their own flagella 

 in the interior of the mother sphere, and the mother sphere at 

 the same time rotating itself. It is a most beautiful sight, and 

 one of which the crushed and broken forms of the photomicro- 

 graph on the screen can give you no idea. The beginnings of 

 differentiation are further seen in the beautiful little fresh water 

 plant called by the quaint name of Batrachospermum, or frog 

 spawn, to which its whorls of cells were supposed to bear a 

 resemblance. The whorls are made up of beaded filaments, and 

 the main axis consists of elongated cells, but certain of the beaded 



