726 SI7MMA.RY OF CUBREXT RESEARCHES BELATDfG TO 



Respiration of Silk-worm Ova.* — Profs. L. Liiciani and A. Piutti 

 have made a long series of experiments on the respiratory phenomena in 

 the eggs of Bomhi/x mori. Their general results are as follows : — The 

 respiratory activity is usually much depressed during hibernation. 

 Lowerinc» of the surrounding temperature has the same eflfect. Dry air 

 causes them to lose moisture, while they gain from damp. With these 

 alterations in humidity the re?piratory activity also varies. Consider- 

 able desiccation at medium temperature may cause absolute latent life. 

 The respiratory activity of hibernating ova varies, cseteris paribus, with 

 the quantity of available oxygen. Limited space brings about progres- 

 sive dimintition of the CO2 eliminated ; when too prolonged asphyxia 

 results. During artificial incubation there is a gradual increase in the 

 quantity of COo developed in unit time ; humidity or dryness favours or 

 depresses activity. The curve of respiratory activity is an index to the 

 internal rate of life or development. The respiratory ratio of CO2 and 

 O2 is not constant, but is a fraction progressively increasing even above 

 unity. " It is probable that during embryonic development there are 

 formed, besides the formative materials, chemical molecules less oxy- 

 genated, and therefore provided with a sum of potential energy always 

 on the increase." 



Mode of Locomotion of Caterpillars. t — M- G. Carlet has been 

 investigating the mode of locomotion of caterpillars. He finds that the 

 ordinary statement that two limbs of the same pair never move simul- 

 taneously in terrestrial locomotion is incorrect. If observation is started 

 on a caterpillar which has come to rest with its body well extended, it 

 is fuund that its first movement is to detach the anal appendage and to 

 approximate it to the one in front by contracting the two intermediate 

 apodal rings. The four pairs of false limbs are then detached in order 

 from behind forwards, and are at the same time pushed forwards by the 

 extension of the two hinder apodal rings. This series of progressive 

 movements of the rings reaches, in the form of a wave, the first two 

 apodal rings of the abdomen, which are held in position by the ap- 

 pendages of the first three rings. These two apodal rings become com- 

 pressed, and the fourth appendage (or one nearest behind them) is 

 approximated to the third appendage, or one nearest in front of them. 

 This third appendage is immediately raised, and, almost simultaneously, 

 though successively, the second and first pairs of appendages are 

 raised. 



We can now understand why it is that the " false legs " are so strong 

 as compared with the others ; they may be appropriately called mooring 

 legs (•' pattes-amarres "), for it is they which maintain the caterpillar and 

 order its progression. Physiologically, they are the true legs, and the 

 true legs (or " pattes ecailleuses ") are the false legs of the caterpillars. 

 The author proposes to do away with the term of false legs, and to 

 replace it by that of membranous legs (" pattes membraneuses "). 



The loss of hooks fiom the membranous legs of Cossus and some other 

 xylophagous caterpillars is correlated with their habitation of trunks in 

 which they hoUow out galleries ; but, as compensation, the masticatory 

 apparatus is exceedingly well developed. The looping caterpillars loop 

 so as to bring their remaining two pairs of membranous legs into 



» Arch. Ital. Biol., ix. (1888) pp. 319-58 (1 pi.), 

 t Comptes Rendua, cvii. (1888) pp. 131-4. 



