NATURE OF THE INVERTEBRATE BRAIN. 27 



single meeting of such a committee before the Association separates 

 would settle a basis of action and compress itself into a working sub- 

 committee. The time for papers and discussions is past ; they have 

 done their work. What the schools and the head-masters want is 

 authoritative guidance the guidance not only of a blue-book, but of 

 a living leadership, central, commanding, and accessible, to which 

 they may look with confidence, and bow without loss of prestige. 



The precision of its dicta will clear up public confusion ; its abil- 

 ity, conscientiousness, and pojmlarity, will overawe the clergy ; schools 

 and universities will listen respectfully to suggestions echoed by their 

 own best men ; and the three great departments of intellectual culture, 

 equal in credit, appliances, and teaching power, will bring out all the 

 faculties and elicit the special aptitudes of every English boy. 



" Hinc omne principium, hue refer exitum." l 



Nature. 



-+*+- 



NATURE OF THE INVERTEBRATE BRAIN. 



By Professor H. CHAELTON BASTIAN. 



II. 



IT now remains for us to consider the disposition of the nervous sys- 

 tem in some of the principal types of the sub-kingdom Mollusca. 



These are animals wholly different in kind from those we have 

 just been considering, mostly aquatic, and all of them devoid of 

 hollow, articulated, locomotor appendages. Their organs of vege- 

 tative life attain a disproportionate development. On the other hand, 

 what are termed the " organs of relation " present a wide range of 

 variation, as may be imagined from the fact that while some of the 

 simplest representatives of the Mollusca consist of mere motionless 

 sacs or bags, containing organs of digestion, respiration, circulation, 

 and generation, its more complex forms are active predatory creatures, 

 endowed with remarkable and varied powers of locomotion, and with 

 sense-organs as keen and as highly developed as those of insects. The 

 lower type is represented by the motionless ascidian, and the higher 

 by the active and highly-endowed cuttle-fish. 



Omitting any reference to the Polyzoa, we may turn our attention 

 first of all to the Tunicata, of which the solitary ascidians may be 

 taken as the type. They are marine animals, possessing no powers 

 of locomotion, and having no head. The current of sea-water, serving 

 for respiratory purposes, and, at the same time, containing food-parti- 

 cles, enters a large branchial chamber, through an open, funnel-like 

 projection of the investing tunic of the animal, the orifice of which 



1 With this begin, to this refer the end. 



