ORGANIZATION AND GROWTH 217 
bc). This occurs no matter whether the oral or the anal tube 
is incised. Fig. 55 illustrates such a case; an incision 
was made into the oral tube; a week later ocelle had 
formed along both edges of the wound. The foot is not 
indicated in the drawing. Ciona intestinalis, therefore, 
behaves not so much as Cerianthus, but 
more like certain Hydroids, in which we 
have to assume a movement of formative 
substances in two directions. I do not 
think that anyone will be inclined to 
believe that the general causes underly- 
ing the formation of organs are deter- 
mined by the position which the animal 
FIG, 57. occupies in the animal scale. 
2. I have still to describe what occurs after the ocellz are 
formed. All the elements of the cut edge begin to grow in 
length, and a new tube springs from the cut edge. The ani- 
mal of Fig. 55 had assumed the form 
shown in Fig. 57 four weeks later. A new 
third tube had been formed at a. This 
continued to grow in length, and attained 
not only the size of the normal tube, but 
usually became even longer than this.’ 
If’ several incisions are made simulta- 
neously into the same animal, several new 
tubes may be formed at once. The ani- 
mal in Fig. 58 has four such tubes. 
FIG, 58 
VII. EXTIRPATION AND REGENERATION OF THE CENTRAL 
NERVOUS SYSTEM IN CIONA INTESTINALIS 
1. Much more remarkable than that just described is 
another phenomenon of regeneration in this animal—namely, 
1Dr. P. Mingazzini made experiments upon Ciona intestinalis similar to those 
which I have described, and also found that a third tube is formed when the mantle 
of Ciona is incised. While at work upon paper vi I obtained his published account 
of these experiments:— P. M1nGAzziIniI, Bolletino della Societa di Naturalisti 
(Napoli, 1891). 
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