392 Miscellaneous. 



a well-developed proboscis and intestine, and therefore are certainly 

 fitted for the reception of food. 



While the males run briskly about in all directions upon the 

 twigs, the females wander slowly but uninterruptedly downwards, 

 that is towards the trunk. Of course, during this progress they are 

 met with by the rambling males, and I had frequent opportunities 

 of observing them in copula. The fertilized females then crawl 

 away, and thus it happens that one usually finds many more males 

 than females. The latter creep upon the somewhat thicker branches 

 into the fissures of the bark, and especially under the appendages at 

 the base of the leaves, the so-called " Stollen," and here deposit their 

 eggs. The females are easily found here, living or dead, along with 

 the eggs. The latter are about 0'5 millim. in length and 0*22 

 millim. in thickness, enveloped in a little whitish wool. IJsually 

 two or three eggs lie together, and I regard it as not impossible that 

 they are deposited by one female, as the latter might no doubt take 

 nourishment, and so, after depositing the first egg, bring a second 

 or even a third to maturity. I could detect the dead females and 

 their eggs not only upon the twigs but also under scales of bark on 

 the trunk itself. However, the firs on which I made these observa- 

 tions are still young trees, about 5-6 metres in height. 



I observed the flying parthenogenetic females on the 19th of 

 June. As many galls were then emptied, males and females were 

 already present. I found the fertilized eggs deposited under the 

 bark on the 2nd of July, and in all that came under observation 

 the blastoderm was already developed. In this condition they 

 remained until now (July 23 *) according to observations made 

 concurrently upon twigs in the open and preserved in glasses in the 

 house. We may assume with certainty that from these eggs pro- 

 ceeds the wingless hybernating generation which we find in October 

 at the bottom of the buds. 



Hence we now perfectly know the developmental cycle of Chermes. 

 It may be summarized as follows : — 



1. A hybernating, wingless, parthenogenetic generation ; 



2. A winged parthenogenetic generation ; 



3. A generation of male and female wingless animals, from the 



fecundated eggs of which the first generation is again 



produced. 

 The whole course of development thus closely approaches that of 

 Phylloxera, the only difi'erence being that in Chermes the wingless 

 females proceeding from the fecundated eggs directly produce the 

 winged generation, while in Phylloxeixi a greater number of wing- 

 less generations intervenes between them. — Biologisches Centralblatt, 

 September 15, 1887, Band vii. pp. 417-420. 



* The eggs remained in the same stage of development until August 14 

 (when the proof was corrected). 



