396 



SCIENCE PROGRESS 



been carried out but the result is sufficiently striking to merit 

 attention. 



The assumption that the ratio d/l may be constant for the 

 Annelids is by no means so unreasonable as might appear at 

 first sight. The structure of the worms is extremely rudimentary, 

 the major portion of their length consisting of digestive organs 

 and intestines of the simplest type. Consequently the longer 

 the worm the longer is the digestive tract and the greater the 

 amount of food that can be dealt with ; hence the bigger the 

 worm. This, of course, is no proof that d/l is constant but it 

 shows that such might easily be the case, as the above results 

 indicate. Individual specimens of the same species may be 

 expected to vary just a little, as also the different species them- 

 selves, from one another but for approximate calculations these 

 mathematical relationships may prove very useful. Thus, 

 granted that the ratio of length to diameter is constant, by 

 determining the weight (in grams) of any worm, we can calculate 

 its volume, diameter, length and surface area — factors of interest 

 from agricultural and horticultural points of view. 



Carbon Dioxide excreted by Worms. — In order to deter- 

 mine the weight of carbon dioxide excreted by worms the 

 apparatus shown in the figure was fitted up. The worms were 



din, 



&s}uTatov 



"Potash 



■poCa-sli 



placed in the flask B ; in the case of the larger species this 

 contained glass stoppers so that the worms could crawl about 

 more easily. Air freed from carbon dioxide by passage through 

 the potash in A was slowly aspirated through the apparatus, 

 being dried by the U-tubes C and D which contained calcium 

 chloride. The bulbs E contained caustic potash which absorbed 

 any carbon dioxide breathed into the air by the worms. By 

 weighing E before and after each experiment the weight of this 

 carbon dioxide was determined. F and G are two guard drying 

 tubes, F being weighed with E in case any moisture should 



