TRANSACTIONS OF SECTION U. 



753 



Hop-shoots as early as ]\rarch 29, and that of Mr. A. Ward, who experimented 

 with surface dressings near Hereford, Miss Ormerod concludes that attack on the 

 Hop begins in spring from wingless females which come up from the Hop hills ; 

 and as a corollary, that dressings to prevent such ascent are strongly to be 

 recommended. It is quite within the range of possibility, and what is kiaown of 

 aphid life, that where the winters are mild, with scarcely any frost, this Phorodon 

 may continue on the Hop from one year to another in the parthenogenetic con- 

 dition. If such is ever the case in England you have a somewhat different set 

 of facts to deal with here from what we have in America. But for the reasons 

 already stated in abstract, from many other detailed observations which it would 

 be tedious to record here, as well as from the ease with which erroneous con- 

 clusions are arrived at, where not checked and proved by the most competent 

 and careful study, I shall be inclined to believe that the facts in England are essen- 

 tially the same as I have found them in America, imtil convincing and trustworthy 

 evidence to the contrary be forthcoming. Mr. Whitehead may have had another 

 species under observation, and Mr. Ward's surface dressings may have acted by 

 repelling the winged female migrating from Prunus, in the same way that buck- 

 wheat sown among the Hops is believed to do with us. 



3. Arteries of the Base of the Brain. By Bertram C. A. Windle, 

 M.A., M.D. (Dublin), Professor of Anatomy in the Queen's CoUerje, 

 Birmingham. 



The abnormalities of the basal arteries of the brain have not to my knowledge 

 been hitherto described from any extended observations. I have notes of two 

 hundred cases, of which the following paper is a summary : — 



Anterior Communicating Artery. 



Double 



Triple 



Union and subsequent division of anterior cerebrals 



>' _ » » J) 

 with a communicating .... 

 None from union of two anterior cerebral arteries 

 „ absence of one anterior cerebral artery 

 A second communicating running into first 

 A median artery derived from communicating 

 Normal 



together 



Anterior Cerebral Arteries. 

 A third or median from anterior communicating 

 None on R., but twig from left middle cerebral 

 „ „ „ internal carotid 

 Complete union of two arteries 

 Normal 



14 

 1 

 6 



2 

 1 

 2 

 6 

 9 

 169 



9 

 1 

 1 

 1 



183 



Posterior Cerebral Arteries. 



From carotid on R 11 



» » L 9 



„ ,, both sides ....... 4 



Two on L. side, one from basilar, one from carotid, with slight 



anastomosis .......... 1 



Normal 175 



Posterior Communicating Arteries. 



None on R 9 



„ L 13 



„ either 3 



1887. 3 



