134 ENEMIES OF APHIDES. 



EXPLANATION OF PLATES YIII. and IX. 





Plate VIIL 



Fig. 1. — Proboscis of Syrphus luniger seen obliquely, and having the 

 near labial palpus removed : — a, The bottom of the mouth ; 

 6, the tongue (ligula) ; c, the horny upper lip ; k, k, the lobes 

 of the under lip ; s, the salivary duct. 



2. — Enlarged view of the extremity of the upper lip, showing the 

 teeth and spiny processes. Below is shown the extremity of 

 the tongue. 



3. — Pollens from the oesophagus, stomach, and rectum of Rhingia, 

 Syrphus, and EHstalis. 



4. — Gastric gland from human stomach. 



5. — Spermathecse and spermatic canals from female Eristalis tenax 



6. — One of the spermathecpe of Eristalis before expansion, show- 

 ing the separate capsules and the enveloping membrane. 



Plate IX. 



Fig. 1. — The renal organs of S. luniger, in situ, in the expansion of 

 the rectum, showing their insertion through the partially 

 transparent walls of the rectum and the distribution of the 

 tracheal trunks. 



2. — One of the papillae removed and carefully focussed for the 

 underside of the outer membrane, so as to exhibit the termi- 

 nation of the tracheal branches. 



3. — The same, seen in section. 



4. — One of the papillae of Eristalis tenax, seen in situ, displaying 

 the arrangemeut of the tracheal tubes and the internal cavity. 

 Pollen-grains are seen floating free in the rectum. 



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The question whether the intensity of the radiation of heat by 

 the sun is affected by its condition as to spots has been studied 

 by M. R. Savelief, of Kiev, in the light of observations made in 

 the spring and the fall of the years 1890, 1891, and 1892. The 

 results point to an affirmative answer, the radiation being greater 

 as the sun-spot activity augments. A variation in one series of the 

 experiments is interpreted as indicating that the increase is 

 dependent, not so much on the absolute number of the spots as 

 upon the intensity of their evolution ; or it may mean that it is 

 immediately consecutive on their diminution. — Pop. Set. Mon. 



