ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
573 
rather seem to belong to the body-musculature, and to have been 
specially differentiated from them. 
In adult scolices, at any rate, there are no intermediate stages 
between the rostellum and the muscular cone, though the organs are, 
no doubt, homologous. The innervation of the rostellum is effected 
by very fine nerve-fibres which can be rendered visible by gold. 
Ligula as Food in Italy.* — Dr. F. S. Monticelli points out that 
though Italians may eat Ligula with the piscine host that contains it 
they do not make a special dish of it, as is generally supposed. 
5. Incertse Sedis. 
Development of Balanoglossus. | — Mr. T. H. Morgan gives the 
details of his investigation. The general phenomena of growth as shown 
by Tornaria present a remarkable series of changes. During the earlier 
stages an immense increase in size takes place ; as the digestive tract 
does not increase to nearly the same extent as the walls of the body, the 
space between the walls is much larger than at first. 
In the second phase of larval growth a continuous decrease in size 
takes place, but during this period no new organs are formed. In the 
third period there is again increase, but this takes place in all the 
organs simultaneously, and not, as in the early stages, at the expense 
of one set of structures only. One fact which the author regards as of 
capital importance is that the increase in length of the young worm is 
due to a general interstitial growth ; the elongation of the posterior 
metamere is not due to apical growth. 
With regard to the metamerism of Balanoglossus it is considered as 
having three pairs of body-cavities, separated from one another by 
transverse septa with double walls. It is suggested that if the creature 
was shortened, the proboscis changed into a pre-oral lobe, and the 
posterior region made of the same length as the collar, no one would 
doubt that we were dealing with a metameric animal of three segments. 
If we look upon Balanoglossus as a form profoundly modified to fit it for 
life in the sand, regard the proboscis as a pre-oral lobe (and head- 
segment) enlarged as a boring organ, and the posterior metamere 
immensely prolonged, we cannot escape the conclusion that Balano- 
glossus is metameric. 
As it may be said that the collar-pores and series of gill-openings 
arise from a pair of invaginations of the ectoderm the question arises 
whether this pair of invaginations may not be looked upon as the 
beginning of an atrium. Merely throwing out this suggestion the 
author notes the resemblances between Amjphioxus and Balanoglossus , and 
urges that the characters of the gill-slits point to a common origin for 
them and for Ascidians. 
Comparing his New-England forms with others Mr. Morgan remarks 
that in them the collar-cavities arise each from a single proliferation of 
endodermal cells, and the third pair of body-cavities arise as solid 
evaginations from the endoderm ; in the Bahama form, on the other 
hand, the collar-cavities and the last pair of cavities have a mesenchy- 
* Extract from Boll. Soc. Natural. Nap., viii. (1894) fasc. 1, 3 pp. 
f Journal of Morphology, ix. (1894) pp. 1-86 (6 pis.). 
1894 2 R 
